Some fruit bats eat up to twice their body weight in sugary mangoes, bananas, or figs every day to not only survive, but thrive. Unlike humans, these flying mammals can have an essentially permanent sweet tooth and do not develop some of the negative health consequences such as diabetes. A study published January 9 in the journal Nature Communications found that genetic adaptations have helped keep their sugary diets from becoming harmful. 

[Related: How do bats stay cancer-free? The answer could be lifesaving for humans.]

The study could have future implications for treating diabetes, which affects an estimated 38 million Americans, according to the Centers for Disease Control and Prevention (CDC). It is the eighth leading cause of death in the United States and the leading cause of kidney failure, lower-limb amputations, and adult blindness.

“With diabetes, the human body can’t produce or detect insulin, leading to problems controlling blood sugar,” study co-author and University of California, San Francisco geneticist Nadav Ahituv said in a statement. “But fruit bats have a genetic system that controls blood sugar without fail. We’d like to learn from that system to make better insulin-or sugar-sensing therapies for people.”  

Fruit bats vs. insect bats

Every day, fruit bats wake up after about 20 hours of sleep and feast on fruit before returning back to their caves, trees, or human-built structures to roost. To figure out how they can eat so much sugar and thrive, the team in this study focused on how the bat pancreas and kidneys evolved. The pancreas is an abdominal organ that controls blood sugar. 

Researchers compared the Jamaican fruit bat with an insect-eating bat called the big brown bat. They analyzed the gene expression–which genes were switched on or off–and regulatory DNA that controls gene expression. To do this, the team measured both the gene expression and regulatory DNA present in individual cells. These measurements show which types of cells primarily make up the bat’s organs and also how these cells regulate the gene expression that manages their diet. 

They found that the compositions of the pancreas and kidneys in fruit bats evolved to accommodate their sugary diet. The pancreas had more cells to produce insulin, an essential hormone that tells the body to lower blood sugar. It also had more cells that produce another sugar-regulating hormone called glucagon. The fruit bat kidneys had more cells to trap scarce salts and electrolytes as they filter blood.  

Changes in DNA

Taking a closer look at the genetics behind this, the team saw that the regulatory DNA in those cells had evolved to switch the appropriate genes for fruit metabolism on or off. The insect-eating big brown bats had more cells that break down protein and conserve water and the gene expression in these cells was calibrated to handle a diet of bugs. 

[Related: Vampire bats socially distance when they feel sick.]

“The organization of the DNA around the insulin and glucagon genes was very clearly different between the two bat species,” study co-author and Menlo College biologist Wei Gordon said in a statement. “The DNA around genes used to be considered ‘junk,’ but our data shows that this regulatory DNA likely helps fruit bats react to sudden increases or decreases in blood sugar.” 

While some of the fruit bat’s biology resembled what is found in humans with diabetes, the bats are not known to have the same health effects.

“Even small changes, to single letters of DNA, make this diet viable for fruit bats,” said Gordon. “We need to understand high-sugar metabolism like this to make progress helping the one in three Americans who are prediabetic.” 

Studying bats for human health

Bats are one of the most diverse families of mammals and everything from their immune systems to very particular diets are considered by some scientists to be examples of evolutionary triumph. This study is one of recent examples of how studying bats could have implications for human health, including in cancer research and virus prevention. 

For this study, Gordon and Ahituv traveled to Belize to participate in an annual Bat-a-Thon, where they took census of wild bats and field samples. One of the Jamaican fruit bats that they captured at the Bat-a-Thon was used to study sugar metabolism.  

“For me, bats are like superheroes, each one with an amazing super power, whether it is echolocation, flying, blood sucking without coagulation, or eating fruit and not getting diabetes,” Ahituv said. “This kind of work is just the beginning.” 

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The male sex organs of the animal kingdom come in all shapes and sizes from some that look like a bottle opener to genital stingers. For mammals, penetrative sex with a penis is needed to successfully mate. However, scientists have documented the first non-penetrative sex ever seen in a mammal. The mating technique was observed in the serotine bat (Eptesicus serotinus) and it is described in a study published November 20 in the journal Current Biology.

The mysteries of bat sex

Serotine bats are quite common in Europe and Asia, but the intricacies of bat sex remain elusive. Most previous observations of bats mating have only offered a glimpse of the backs of mating pairs. But in the new study, a team from the University of Lausanne in Switzerland and a bat rehabilitation center in Ukraine got lucky. 

[Related: How echolocation lets bats, dolphins, and even people navigate by sound.]

“By chance, we had observed that these bats have disproportionately long penises, and we were always wondering ‘how does that work?’,” study co-author and University of Lausanne evolutionary biologist Nicolas Fasel said in a statement. “We thought maybe it’s like in the dog where the penis engorges after penetration so that they are locked together, or alternatively maybe they just couldn’t put it inside, but that type of copulation hasn’t been reported in mammals until now.” 

The team placed cameras behind a grid that the bats could climb hoping to get footage of their genitals and mating from one side of the grid. They found that bats’ penises are roughly seven times longer than their partners’ vaginas. Each has a “heart-shaped” head that is also seven times wider than the common bat vaginal opening. This size and shape would make penetration after an erection impossible. The study shows that instead of functioning as a penetrative organ, the penis is more like an extra arm. It pushes the female’s tail sheath out of the way to engage in contact mating, similar to cloacal kissing in birds. Instead of penetration, the birds touch their two rear orifices called the cloaca together for only a few seconds, but long enough for sperm to be released.

The bat sex detectives

Fasel collaborated with bat enthusiast and citizen scientist Jan Jeucker, who filmed hours of footage of the serotine bat in a church attic in the Netherlands. The team analyzed 97 mating events—93 from the Dutch church and four from the Ukrainian bat rehabilitation center. During the recordings, the team did not see a single incidence of penetration. The erectile tissues of the bat penis were completely enlarged before they made any contact with the vulva. The male bats grasped their partner’s nape and moved their pelvis like a probe until it made contact with the vulva. Once contact was made, the pair remained still. These interactions lasted less than 53 minutes on average, but the longest event extended to 12.7 hours. 

After copulation, the researchers saw that the female bats had wet abdomens. They believe this dampness indicates the presence of semen, but more research is needed to confirm if sperm was actually transferred during these assumed mating events.

[Related: What bats and metal vocalists have in common.]

The team also characterized the form of serotine bat genitalia by measuring the erect penises of live bats that were captured as part of other research studies. The necropsies on bats that had died at bat rehabilitation centers revealed how much longer and wider the serotine bat penises were compared to the bat vaginas. The penises are also about a fifth as long as the bats’ head to body length. Female serotine bats also have unusually long cervixes, which potentially helps them select and store sperm.

The team believes that the bats may have evolved their oversized penises as a way to push aside the female tail membranes.  

“Bats use their tail membranes for flying and to capture the insects, and female bats also use them to cover their lower parts and protect themselves from males,” said Fasel. “But the males can then use these big penises to overcome the tail membrane and reach the vulva.”

The team plans to study bat mating behavior in more natural contexts and further investigate penis morphology and mating behavior in other bat species. 

“We are trying to develop a bat porn box, which will be like an aquarium with cameras everywhere,” says Fasel.

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After getting bit by a bat bug at a recent conference, Armin Scheben had a literal and figurative itch to study bats. The blood-sucking insect is one of many disease-causing parasites that latch themselves onto the flying mammals—yet, bats rarely get sick in the same way humans do. 

Mammalian immune systems evolve fast as species are always challenged with new pathogens in their environment. “You need to constantly keep pace with new bad guys that are trying to infect and hurt you,” says Scheben, who is a postdoctoral fellow in population genomics at Cold Spring Harbor Laboratory (and has since recovered from the bite). And while he has studied the genetic adaptations of several mammals, they pale in comparison to the ones that have given bats the ability to fight off infections so effectively.

In a new study published today in the journal Genome Biology and Evolution, Scheben and his team have identified the genes that have contributed to bats’ rapidly evolving immune system and their unique ability to evade deadly viruses and even cancer. Understanding how bats survive diseases could inspire new immune treatments for humans and potentially help prevent another pandemic. 

[Related: A ‘living’ cancer drug helped two patients stay disease-free for a decade]

The authors analyzed the DNA of 15 different bat species to get a clearer picture of how their genes evolved over time. They fully sequenced the genomes of two bat species, the Jamaican fruit bat and the Mesoamerican mustached bat, and gathered the other species from preexisting datasets. 

They then compared the bat genomes to that of humans, mice, and other cancer-susceptible mammals, focusing their attention on the sequences that encode proteins responsible for causing or preventing diseases. To start, they lined up the homologous genes, or shared genes among different species inherited from a shared evolutionary ancestor. (It’s like comparing apples with apples, explains Scheben.) With each homologous gene, they hypothesized two scenarios: if bats lost it or if it mutated. If the flying mammals completely lost the gene, it suggests that the omission is important in fighting disease. But if it remained with subtle changes in the DNA sequence that are only found in bats, it could show a change in gene function that somehow helps the group stay healthy.

In the end, the most striking changes the team detected were in type one interferon (IFN) genes, which are important for controlling inflammatory responses to infections. Specifically, they observed a shift in the number of antiviral IFN-α and IFN-ω genes. For instance, three bat species seemed to have lost all of their IFN-α while increasing the number of IFN-ω genes.

According to Scheben, the most surprising finding was observing the loss of IFN-α and addition of more IFN-ω genes, “which hadn’t been reported at all before.” The results suggest the new IFN-ω and missing IFN-α genes are important in bats for resisting viral infections while preventing overactive inflammatory responses—a feature that has made inflammation a double-edged sword in humans.

But while the findings have put geneticists one step closer to understanding how bats evolved their unique ability to resist cancer and viruses, it doesn’t paint a complete picture. The study focuses only on the genetics of innate immunity (the immediate immune response to infected cells), says Tony Schountz, a professor at the Center of Vector-Borne Infectious Diseases at Colorado State University, who was not involved in the study. It does not include information about bats’ adaptive immunity, which consists of the antibody and T-cell responses that many mammals use to fight diseases. “These are two very different, but complementary components of immunity,“ Schountz explains. “Nearly all of the focus on bat immunity to date has been on innate immunity, principally because the study of adaptive immunity requires live animals, which few groups have and is much more complicated.”

Even without a full set of information, understanding the changes in the bats’ innate immune system could help scientists develop genetic treatments for humans that decrease susceptibility to certain illnesses. We can also learn which genes drive bats’ 20- to 30-year lifespans, or how their bodies have adapted to process sugar-rich foods without developing the negative consequences seen in people with diabetes. 

[Related: What bats and metal vocalists have in common]

And though bats have gained a notorious reputation for their purported role in spreading COVID, Scheben hopes that these new findings could point researchers in the right direction in understanding how the animals host such potent viruses and parasites without getting very sick. One day, he says, that information could be used to prevent our species from suffering major symptoms when infected. “It’s absolutely not misplaced to believe that studying bats could help us prevent another pandemic.”

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This article was originally published on Undark.

It could have been a scene from Jurassic Park: ten golden lumps of hardened resin, each encasing insects. But these weren’t from the age of the dinosaurs; these younger resins were formed in eastern Africa within the last few hundreds or thousands of years. Still, they offered a glimpse into a lost past: the dry evergreen forests of coastal Tanzania.

An international team of scientists recently took a close look at the lumps, which had been first collected more than a century ago by resin traders and then housed at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany. Many of the insects encased within them were stingless bees, tropical pollinators that can get stuck in the sticky substance while gathering it to construct nests. Three of the species still live in Africa, but two had such a unique combination of features that last year, the scientists reported them to be new to science: Axestotrigona kitingae and Hypotrigona kleineri.

Species discoveries can be joyous occasions, but not in this case. Eastern African forests have nearly disappeared in the past century, and neither bee species has been spotted in surveys conducted in the area since the 1990s, noted coauthor and entomologist Michael Engel, who recently moved from a position at the University of Kansas to the American Museum of Natural History. Given that these social bees are usually abundant, it’s unlikely that the people looking for insects had simply missed them. Sometime in the last 50 to 60 years, Engel suspects, the bees vanished along with their habitat.

“It seems trivial on a planet with millions of species to sit back and go, ‘Okay, well, you documented two stingless bees that were lost,’” Engel said. “But it’s really far more troubling than that,” he added, because scientists increasingly recognize that extinction is “a very common phenomenon.”

The stingless bees are part of an overlooked but growing trend of species that are already deemed extinct by the time they’re discovered. Scientists have identified new species of bats, birds, beetles, fish, frogs, snails, orchids, lichen, marsh plants, and wildflowers by studying old museum specimens, only to find that they are at risk of vanishing or may not exist in the wild anymore. Such discoveries illustrate how little is still known about Earth’s biodiversity and the mounting scale of extinctions. They also hint at the silent extinctions among species that haven’t yet been described — what scientists call dark extinctions.

It’s critical to identify undescribed species and the threats they face, said Martin Cheek, a botanist at the Royal Botanic Gardens, Kew, in the United Kingdom, because if experts and policymakers don’t know an endangered species exists, they can’t take action to preserve it. With no way to count how many undescribed species are going extinct, researchers also risk underestimating the scale of human-caused extinctions — including the loss of ecologically vital species like pollinators. And if species go extinct unnoticed, scientists also miss the chance to capture the complete richness of life on Earth for future generations. “I think we want to have a full assessment of humans’ impact on nature,” said theoretical ecologist Ryan Chisholm of the National University of Singapore. “And to do that, we need to take account of these dark extinctions as well as the extinctions that we know about.”

Many scientists agree that humans have pushed extinctions higher than the natural rate of species turnover, but nobody knows the actual toll. In the tens of millions of years before humans came along, scientists estimate that for every 10,000 species, between 0.1 and 2 went extinct each century. (Even these rates are uncertain because many species didn’t leave behind fossils.) Some studies suggest that extinction rates picked up at least in the past 10,000 years as humans expanded across the globe, hunting large mammals along the way.

Islands were particularly hard hit, for instance in the Pacific, where Polynesian settlers introduced pigs and rats that wiped out native species. Then, starting in the 16th century, contact with European explorers caused additional extinctions in many places by intensifying habitat loss and the introduction of invasive species — issues that often continued in places that became colonies. But again, scientists have a poor record of biodiversity during this time; some species’ extinctions were only recognized much later, most famously the dodo, which had disappeared by 1700 after 200 years of Europeans hunting and then settling on the island in the Indian Ocean island it inhabited.

Key drivers of extinction, such as industrialization, have ramped up ever since. For the past century, some scientists have estimated an average of 200 extinctions per 10,000 species— levels so high that they believe they portend a mass extinction, a term reserved for geological events of the scale of the ordeal that annihalated the dinosaurs 66 million years ago. Yet some scientists, including the authors of those estimates, caution that even these numbers are conservative. The figures are based on the Red List compiled by the International Union for Conservation of Nature, or IUCN, a bookkeeper of species and their conservation statuses. As several experts have noted, the organization is slow to declare species extinct, wary that if the classification is wrong, they may cause threatened species to lose protections.

The Red List doesn’t include undescribed species, which some estimate could account for roughly 86 percent of the possibly 8.7 million species on Earth. That’s partly due to the sheer numbers of the largest species groups like invertebrates, plants, and fungi, especially in the little-explored regions around the tropics. It’s also because there are increasingly fewer experts to describe them due to a widespread lack of funding and training, noted conservation ecologist Natalia Ocampo-Peñuela of the University of California, Santa Cruz. Ocampo-Peñuela told Undark that she has no doubt that many species are going extinct without anyone noticing. “I think it is a phenomenon that will continue to happen and that it maybe has happened a lot more than we realize,” she said.

Studies of animal and plant specimens in museum and herbaria collections can uncover some of these dark extinctions. This can happen when scientists take a closer look at or conduct DNA analysis on specimens believed to represent known species and realize that these have actually been mislabeled, and instead represent new species that haven’t been seen in the wild in decades. Such a case unfolded recently for the ichthyologist Wilson Costa of the Federal University of Rio de Janeiro, who has long studied the diversity of killifish inhabiting southeastern Brazil’s Atlantic Forest. These fish live in shady, tea-colored acidic pools that form during the rainy season and lay eggs that survive through the dry period. These fragile conditions make these species extremely vulnerable to changes in water supply or deforestation, Costa wrote to Undark via email.

In 2019, Costa discovered that certain fish specimens collected in the 1980s weren’t members of Leptopanchax splendens, as previously believed, but actually represented a new species, which he called Leptopanchax sanguineus. With a few differences, both fish sport alternating red and metallic blue stripes on their flanks. While Leptopanchax splendens is critically endangered, Leptopanchax sanguineus hasn’t been spotted at all since its last collection in 1987. Pools no longer form where it was first found, probably because a nearby breeding facility for ornamental fish has diverted the water supply, said Costa, who has already witnessed the extinctions of several killifish species. “In the case discussed here, it was particularly sad because it is a species with unique characteristics and unusual beauty,” he added, “the product of millions of years of evolution stupidly interrupted.”

Similar discoveries have come from undescribed specimens, which exist in troves for diverse and poorly-studied groups of species, such as the land snails that have evolved across Pacific Islands. The mollusk specialist Alan Solem estimated in 1990 that, of roughly 200 Hawaiian species of one snail family, the Endodontidae, in Honolulu’s Bishop Museum, fewer than 40 had been described. All but a few are now likely extinct, said University of Hawaii biologist Robert Cowie, perhaps because invasive ants feasted off the snails’ eggs, which this snail family carries in a cavity underneath their shells. Meanwhile, Cheek said he’s publishing more and more new plant species from undescribed herbaria specimens that are likely already extinct in the wild.

Sometimes, though, it’s hard to identify species based on individual specimens, noted botanist Naomi Fraga, who directs conservation programs at the California Botanic Garden. And describing new species is not often a research priority. Studies that report new species aren’t often cited by other scientists, and they typically also don’t help towards pulling in new funding, both of which are key to academic success, Cheek said. One 2012 study concluded it takes an average of 21 years for a collected species to be formally described in the scientific literature. The authors added that if these difficulties — and the general dearth of taxonomists — persist, experts will continue to find extinct species in museum collections, “just as astronomers observe stars that vanished thousands of years ago.”

Museum records may only represent a fraction of undescribed species, causing some scientists to worry that many species could disappear unnoticed. For some groups, like snails, this is less likely, as extinct species may leave behind a shell that serves as a record of their existence even if collectors weren’t around to collect live specimens, noted Cowie. For instance, this allowed scientists to identify nine new and already-extinct species of helicinid land snails by combing the Gambier Islands in the Pacific for empty shells and combining these with specimens that already existed in museums. However, Cowie worries about the many invertebrates such as insects and spiders that won’t leave behind long-lasting physical remains. “What I worry about is that all this squishy biodiversity will just vanish without leaving a trace, and we’ll never know existed,” Cowie said.

Even some species that are found while they are still alive are already on the brink. In fact, research suggests that it’s precisely the newly described species that tend to have the highest risk of going extinct. Many new species are only now being discovered because they’re rare, isolated, or both — factors that also make them easier to wipe out, said Fraga. In 2018 in Guinea, for instance, botanist Denise Molmou of the National Herbarium of Guinea in Conakry discovered a new plant species which, like many of its relatives, appeared to inhabit a single waterfall, enveloping rocks amid the bubbly, air-rich water. Molmou was the last known person to see it alive.

Just before her team published their findings in the Kew Bulletin last year, Cheek looked at the waterfall’s location on Google Earth. A reservoir, created by a hydroelectric dam downriver, had flooded the waterfall, surely drowning any plants there, Cheek said. “Had we not got in there, and Denise had not gotten that specimen, we would not know that that species existed,” he added. “I felt sick, I felt, you know, it’s hopeless, like what’s the point?” Even if the team had known at the point of discovery that the dam was going to wipe it out, Cheek said, “it’d be quite difficult to do anything about it.”

While extinction is likely for many of these cases, it’s often hard to prove. The IUCN requires targeted searches to declare an extinction — something that Costa is still planning on doing for the killifish, four years after its discovery. But these surveys cost money, and aren’t always possible.

Meanwhile, some scientists have turned to computational techniques to estimate the scale of dark extinction, by extrapolating rates of species discovery and extinctions among known species. When Chisholm’s group applied this method to the estimated 195 species of birds in Singapore, they estimated that 9.6 undescribed species have vanished from the area in the past 200 years, in addition to the disappearance of 58 known species. For butterflies in Singapore, accounting for dark extinction roughly doubled the extinction toll of 132 known species.

Using similar approaches, a different research team estimated that the proportion of dark extinctions could account for up to just over a half of all extinctions, depending on the region and species group. Of course, “the main challenge in estimating dark extinction is that it is exactly that: an estimate. We can never be sure,” noted Quentin Cronk, a botanist of the University of British Columbia who has produced similar estimates.

Considering the current trends, some scientists doubt whether it’s even possible to name all species before they go extinct. To Cowie, who expressed little optimism extinctions will abate, the priority should be collecting species, especially invertebrates, from the wild so there will at least be museum specimens to mark their existence. “It’s sort of doing a disservice to our descendants if we let everything just vanish such that 200 years from now, nobody would know the biodiversity — the true biodiversity — that had evolved in the Amazon, for instance,” he said. “I want to know what lives and lived on this Earth,” he continued. “And it’s not just dinosaurs and mammoths and what have you; it’s all these little things that make the world go round.”

Other scientists, like Fraga, find hope in the fact that the presumption of extinction is just that — a presumption. As long as there’s still habitat, there’s a slim chance that species deemed extinct can be rediscovered and returned to healthy populations. In 2021, Japanese scientists stumbled across the fairy lantern Thismia kobensis, a fleshy orange flower only known from a single specimen collected in 1992. Now efforts are underway to protect its location and cultivate specimens for conservation.

Fraga is tracking down reported sightings of a monkeyflower species she identified in herbaria specimens: Erythranthe marmorata, which has bright yellow petals with red spots. Ultimately, she said, species are not just names. They are participants of ecological networks, upon which many other species, including humans, depend.

“We don’t want museum specimens,” she said. “We want to have thriving ecosystems and habitats. And in order to do that, we need to make sure that these species are thriving in, you know, populations in their ecological context, not just living in a museum.”

Katarina Zimmer is a science journalist. Her work has been published in The Scientist, National Geographic, Grist, Outside Magazine, and more.

This article was originally published on Undark. Read the original article.

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In an environment without light, or where sight is otherwise useless, some creatures have learned to thrive by sound. They rely on calls, clicks, and twitters to create a kind of map of their surroundings or pinpoint prey. That ability is called echolocation, and a simple way to understand how it works is to crack open the word itself. 

What is echolocation?

Imagine an echo that locates things. The sound hits an object and bounces back, relaying information about a target’s whereabouts or cues for navigation. When Harvard University zoologist Donald Griffin coined the word “echolocation” in the journal Science in 1944, he was describing how bats rely on sounds to “fly through the total darkness of caves without striking the walls or the jutting stalactites.”

In the decades since, scientists have identified many other animals that use echolocation, aka biosonar. For example, at least 16 species of birds echolocate, including swiftlets and nocturnal oilbirds, which roost deep in South America’s caves. Laura Kloepper, an expert in animal acoustics at the University of New Hampshire, calls this shared ability an example of convergent evolution, in which “you have two unrelated species evolve the same adaptive strategy.” 

How does echolocation work?

To find fish in deep waters, or avoid crashing in the inky night, whales and bats produce loud ultrasonic sounds at frequencies all the way up to 200 kilohertz. That is way beyond human hearing (most adults can’t perceive pitches above 17 kilohertz). 

[Related on PopSci+: 5 sounds not meant for the human ear]

Why do specialized echolocators use ultrasonic sound? “High-frequency sounds give really fine spatial resolution,” Kloepper explains. Hertz is a measure of the distance between each acoustic wave: The higher the hertz, the tighter the wave, and the smaller the detail captured by the vibration of energy in the air. If you were to echolocate in a room, a big, low-frequency wave might simply reflect off a wall, Kloepper says, while an echo from a higher-frequency sound could tell you where the doorway or even the knob was.

Echoes, if you know how to interpret them, are rich in information. As Kloepper explains it, when an animal with the ability hears a reflection, it examines that sound against an “internalized template” of the call it sent out. That comparison of echo versus signal can yield the distance to a target, the direction it might be traveling in, and even its material make-up.

Ultrasonic calls give another bats boost, too—they rely on next-level frequencies to find mates. Many species of moths hunted by bats have evolved ears attuned to these frequencies as a means of survival.

[Related: How fast is supersonic flight?]

To make ultrasound, a bat vibrates a specialized organ in its throat called a larynx. It’s not too different from how the human voice box works, except the bat produces a much higher frequency sound. Certain bat species then release the sound from their mouths, while others screech from the snout, using an elaborate nasal structure nicknamed a nose-leaf. 

Whales

Dolphins, orcas, and other toothed whales echolocate for the same reasons as bats do: to chase down tasty prey and navigate through darkness. But these aquatic mammals emit ultrasound in a completely different way. Inside whale heads, often close to their blowholes, sit lip-like flaps. When the animals push air across the flaps, the appendages vibrate, producing clicks. “It’s just like if you inflate a balloon and let all the air out of that balloon. It makes a pbbft noise,” Kloepper says. 

The curves of dolphin skulls propel that noise into fatty structures at the front of their heads, called melons. These, in turn, efficiently transmit vibrations in seawater. The waves bounce off prey or other objects, but the whales don’t rely on external ears to hear the echo (their ear canals are plugged up with wax). Instead, the vibrations are channeled via their jawbones, where sound is received by fat-filled cavities so thin that light can pass through them. The cavities are near the whales’ inner ears, which sense the echoing clicks. The process can reveal all sorts of details: where a fish is, where it’s going, and how fast it’s swimming.

Shrews

Shrews have sensitive whiskers but poor eyesight. To supplement their senses as they explore their forest and grassy meadow habitats, they might use a coarse form of echolocation, which Sophie von Merten, a mammalogist at the University of Lisbon in Portugal, calls “echo-orientation” or “echo-navigation.” This ability could “give them a hint that there is an obstacle coming,” she says, such as a fallen branch detected by the shrews’ twitters. Their bird-like sounds are faint, but audible to humans. 

The extent of shrew echo-navigation isn’t entirely clear. In a 2020 “experiment, von Merten and a colleague found that, when shrews are introduced to new environments, the wee mammals twitter more frequently. Von Merten says it’s likely they are sensing the unfamiliar location by these vocalizations, but another interpretation could be that the captive animals are stressed. That’s a hypothesis she doesn’t find very convincing, though her ongoing research will measure shrew stress, too.

Could there be other undiscovered creatures out there that echolocate? “I think it’s very likely,” Kloepper says. She adds that it’s hard to tell which animals beyond mammals and birds display the behavior, given “just how little we know about vocalizations of many cryptic species.”

Humans

Unlike bats, people aren’t born with the innate power of echolocation—but we can still make it work. In his original 1944 paper, Griffin discussed a, such as captains listening for echoes of ship horns against cliff faces, or those who are blind following the taps of their canes. 

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A team of scientists from the United States and the Netherlands have discovered a new species of bat based on the oldest bat skeletons ever discovered. The findings are described in a study published April 12 in the journal PLOS One. 

The new species is named Icaronycteris gunnelli (I. gunnelli) in honor of the late Gregg Gunnell, a Duke University paleontologist who died in 2017 and is remembered for his contributions to understanding fossil bats and evolution. 

[Related: How killing vampire bats to slow rabies can go wrong.]

The now extinct I. gunnelli lived in Wyoming roughly 52 million years ago and the current scientific consensus is that bats rapidly diversified on multiple continents during this time in history. There are currently over 1,460 living bat species  found almost all over the world, except for the Earth’s polar regions and a few remote islands. 

The bat skeletons are about 1.5 inches long and were found near Kemmerer, Wyoming in the Green River Formation. The formation spans parts of Wyoming, Colorado, and Utah and is home to an extensive fossil deposit from the early Eocene—about 56 million to 47.8 million years ago.  Scientists have found more than 30 bat fossils in the last 60 years within the formation. Until finding this new species, however, they believed all of them were from the same two extinct species, Icaronycteris index and Onychonycteris finneyi.

“Eocene bats have been known from the Green River Formation since the 1960s. But interestingly, most specimens that have come out of that formation were identified as representing a single species, Icaronycteris index, up until about 20 years ago, when a second bat species belonging to another genus was discovered,” study co-author Nancy Simmons, curator-in-charge of the American Museum of Natural History’s (AMNH) Department of Mammalogy said in statement. Simmons helped describe the second species named Onychonycteris finneyi in 2008, but always thought that there might be even more Eocene bats out there. 

Recently, scientists from the Naturalis Biodiversity Center in the Netherlands began to look closely at Icaronycteris index by collecting measurements and other data from museum specimens to put together a dataset.

“Paleontologists have collected so many bats that have been identified as Icaronycteris index, and we wondered if there were actually multiple species among these specimens,”  co-author and evolutionary biologist Tim Rietbergen said in a statement. “Then we learned about a new skeleton that diverted our attention.”

[Related: Both bats and humans test out talking as infants.]

The well-preserved I. gunnelli skeleton in this study was purchased by a private collector in 2017 and was subsequently purchased by AMNH. The team compared the skeleton with Rietbergen’s extensive bat dataset and saw that it clearly stood out as a new species.

A second fossilized Icaronycteris gunnelli skeleton that was discovered at this same quarry in 1994. It eventually made its way to the Royal Ontario Museum in Toronto and was also identified as this new species. 

While there are fossilized bat teeth from Asia that are slightly older than these skeletons, the two I. gunnelli fossils represent the oldest bat skeletons ever found, according to the team. The I. gunnelli skeletons are also the oldest bat fossils that have been recovered from the Green River Formation, but they are not the most primitive, meaning not the earliest on the bat evolutionary tree. According to the team, this supports the idea that the bats in the region evolved separately from other Eocene era bats.

“This is a step forward in understanding what happened in terms of evolution and diversity back in the early days of bats,” said Simmons.

The post Oldest bat skeleton ever found by paleontologists finally has a name appeared first on Popular Science.

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Plenty of species have traits evolved for more than one purpose. Deer antlers are built-in weapons as well as seductive doe-magnets. Octopus suckers can trap prey in their suction but also taste and smell. Bright colors in frogs signal danger to predators while flaunting reproductive viability to potential mates. The Luna moth has uniquely shaped wings that thwart predation from bats, but what else might they be good for? How does one determine the evolutionary role of a trait? 

In two recent complementary studies published in Behavioral Ecology and Biology Letters earlier this year, researchers expanded our understanding of the adaptation by testing the role of wing tails against sexual selection and bird predation.

Luna moths are native to the Eastern half of North America. Like all silk moths, they have distinctive long, trailing tails on their hindwings, or “twisted, cupped paddles” as lead author of both studies and doctoral student at the Florida Museum of Natural history Juliette Rubin said in a statement. Bats use echolocation to detect the position of objects with reflected sound, but the moth’s wing shape reflects sound waves in a way that makes the flying mammals aim for the ends of their wings. In a flap of a wing, the moth just barely dodges their predators. 

[Related: What bats and metal vocalists have in common]

First, the researchers wanted to see if the wing tails also played a role in sexual selection. When female Luna moths are ready to mate, they perch in one spot and release pheromones. Males, with extremely sensitive antennae, can detect and follow a pheromone trail, according to the University of Florida’s entomology department. Then, the female has her pick of suitors. 

In the first experiment, researchers placed a female moth in a flight box with two males: one with intact wings and one with the wing tails removed. Initial data suggested that females preferred tails over no-tails, but further trials demonstrated otherwise. When researchers removed tails by clipping them, the resulting damage may have hindered these males’ performance in the first trial, allowing the intact males to mate successfully.

They recreated the tail/no-tail experiment by removing tails from both males, and re-gluing them to one male, while placing glue only on the hindwings of the other. Researchers found no significant difference in mating success between them. 

To ensure the glue did not confound the results, researchers conducted an additional experiment with two intact males, one with glue on the hindwings. Similarly, they had equal mating success.

Though their elegance is attractive to us humans, the experiment revealed that Luna moth wing tails aren’t the result of sexual selection. 

Then, researchers wanted to see if the moths’ tails had any obvious drawbacks. They help moths to survive bats, a species that relies on echolocation, but what about visually-oriented predators? 

Luna moths sit still during the day, since flying in broad daylight with their large bright green wings would make them easy targets. To test whether or not their tails would have any impact on daytime predation, researchers wrapped pastry dough around mealworms and molded them to the size and shape of real Luna moths. They attached full wings and wings without tails to each half. They placed the replicas around branches and leaves in an aviary, and introduced Carolina wrens. 

The wrens ate the fake moths at the same rate regardless of wing type, indicating that the tails had no effect on whether or not birds could locate them. Some research suggests that birds rely on search images, mental representations of objects, when they are searching for prey. They use visual cues, such as the shape of moth wings, to distinguish between the prey from patterns in the background. So, the wrens may ignore the hindwing tails, using the overall shape of Luna moths to identify food, according to the press release.

[Related: A new technique reveals how butterfly wings grow into shimmery wonders.]

These experiments show that despite being a noteworthy feature to humans, the Luna moths’ tails do not play a role in attracting a mate, nor do they affect predation by birds.

“When we see these really obvious physical features in animals, we’re often drawn into stories we’ve heard about them,” Rubin said in the statement. “A trait that’s obvious to us, as visual creatures, might not stand out to the predators that hunt them, and the traits that we think are dynamic and alluring might not seem that way to a potential mate.”

The post The alluring tail of the Luna moth is surprisingly useless for finding a mate appeared first on Popular Science.

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Bats are a critical part of ecosystems worldwide and provide a number of significant benefits to humans, including pest control, pollination, and seed disbursement. Of those three, the biggest reason you might want bats around is likely their ability to hunt insects that are hunting you.

I based these bat house plans on a design published by Bat Conservation International, with a few modifications—what woodworker follows plans exactly? My bat box, for example, is two chambers instead of four, simply because of the amount of wood I had available. I also used cedar fence pickets instead of exterior plywood because they were cheaper, and decided not to put a vent on the side due to the cold climate in Massachusetts.

Warning: DIY projects can be dangerous, even for the most experienced makers. Before proceeding with this or any other project on our site, ensure you have all necessary safety gear and know how to use it properly. At minimum, that may include safety glasses, a facemask, and/or ear protection. If you’re using power tools, you must know how to use them safely and correctly. If you do not, or are otherwise uncomfortable with anything described here, don’t attempt this project.

Stats

• Time: 4 to 6 hours
• Material cost: $40 to $60
• Difficulty: moderate

Materials

• 1 box of (3.5-foot-long) ⅝-by-3.5-inch flat-top cedar fence pickets (about 13 boards)
• Wood glue
• 1-inch brad nails
• Exterior painter’s caulk
• Black exterior spray paint

Tools

• Miter saw
• Table saw
• Crosscut sled
• Clamps
• Parallel clamps
• Orbital sander
• Sanding discs (60- and 120-grit)
• (Optional) jointer

How to build a bat house

1. Cut the fence pickets to length on your miter saw. Before jointing wood, always cut the boards down to rough length. This makes flattening easier, and cuts down on the amount of material you’ll need to remove from warped boards.

This bat box consists of three panels, each made from different lengths of wood. Although you can cut the middle and front panel boards exactly the same length because they will be the same size (24 by 18 inches), I did not. I was able to use my wood more efficiently by making the front and back panels from vertical 24-inch boards, and the middle one out of horizontal 18-inch planks. This worked because I could get one 18- and one 24-inch board out of each 42-inch fence picket. Here’s how my panel groupings broke down:

• Back panel: six (30-inch) boards
• Middle panel: eight (18-inch) boards
• Front panel: six (24-inch) boards

2. Joint one face and edge on each board. If you don’t have a jointer, you can skip face jointing for this project, and just edge joint on your table saw. But if you have access to a jointer, cleaning up one face will make assembly easier.  

• Note: The jointed faces of the boards should be the outside of your panels. I left the insides of my panels rough so the bats would have an easier time clinging to them, though we will add more texture later.

3. Trim all the boards to width on your table saw. I picked 3 inches to make all of the math easy, even though I wound up with a bit more waste than was strictly necessary. 

4. Glue the front and back panels together. Building panels is one of the core skills required for many woodworking projects, and a good set of parallel clamps will help immensely. Fully open your clamps and set them down side by side, about 2 inches closer together than the full width of your panels. Lay the boards across them, jointed faces down, and press the boards together by hand to make sure all the seams are tight. If they aren’t, clean them up on your jointer or table saw.

Once you’re satisfied with the layout, spread a line of glue on each touching edge of the boards, and press them together. Tighten the clamps until glue squeezes out of the seams. Then add two more clamps between and parallel to the first pair of clamps, but on top of the panel instead of below. This will give the panel a bit more stability and reduce the chance of warping.

• Pro tip: To help prevent warping even more, use cauls on each end of the panel (I skipped this step and regretted it because I got a bit of warp that I had to fix).

5. Cut the rails for the panels. This bat house has two chambers, which basically means it’s two boxes stacked together. To create those boxes, you’ll need two pairs of rails for the panels to sit on to form cavities for the bats to roost in. I crafted my rails from the scraps left over from building the panels. I had several 12-inch-long boards, so I cut eight ⅞-inch strips out of those to make the four rails.

6. Cut grooves into both sides of the 18-inch boards for the middle panel. The bats most likely to roost in a box are used to spending time in trees, says David Mizejewski, a naturalist at the nonprofit National Wildlife Federation. This means the box should be textured like a tree to give the animals something to hold on to. Shallow grooves spaced between ¼- and ½-inch apart work nicely, according to Bat Conservation International.

[Related: What bats and metal vocalists have in common]

Set the height of your table saw to between 1/16 and ⅛ inch high. Then set the fence about a quarter-inch from the blade, and run all of your middle panel boards over it, on both faces. Then move the fence another quarter inch away from the blade and run the boards again. Continue until you’ve cut grooves along both faces of all eight boards.

• Note: Older bat house plans might recommend installing wire mesh, but many conservationists now recommend against that because there’s a chance the bats will get tangled in it.

7. Square the front and back panels, then cut grooves. Once these two panels are dry according to the glue manufacturer’s instructions, trim both ends of one panel, squaring them to its edges. The easiest tool for this is a crosscut sled on your table saw. Once the ends are square, leave the panel on the sled to cut graspable grooves. Set the blade height between 1/16 and ⅛ inch, and cut grooves every quarter-inch or so. These don’t have to be precise. Just slide the panel over a bit at a time. Repeat this step with the other panel.

• Warning: This is the sort of operation where it’s easy to lose focus and hurt yourself by grabbing or moving at the wrong place or wrong time. Make sure you pull the sled all the way back so you can freely move the panel without touching the blade.

8. Assemble the first chamber. Lay the back panel down flat with the textured and grooved side facing up. Place the rails onto the face, aligned with each edge and with about 2 inches between the top of the panel and the start of each rail. This gap leaves room to hang the box. Glue the rails in place and further secure them with 1-inch brad nails.

Then glue and brad nail the 18-inch boards across the rails to form the middle panel. Clamp everything together until the glue dries.

9. Assemble the second chamber. Once the first chamber is secure and dry, build the second, gluing rails to the middle panel and securing the front panel to those with glue, clamps, and brad nails.

10. Add a roof. Glue and brad nail one final board, 18 inches long and 3 inches wide, across the top of both cavities as a roof. Rather than cutting a dedicated piece to size, however, I used some of the cutoff scraps I had, making sure to butt them as tight together as I could. 

11. Sand everything smoothish. This is one of those magical projects where sanding doesn’t matter too much. I used 60-grit sandpaper on my orbital sander to clean up any boards that were slightly out of alignment or particularly rough. Then I sanded everything with 120-grit paper. Because the bat box will be painted, hung quite high, and won’t be touched a lot (by people anyway), there was no point in going further than that.  

12. Fill in all the gaps with caulk. “Make sure that all of the seams are tight and there aren’t a lot of gaps because heat is the key thing,” says Mizejewski. “The bats really want it to stay warm in there. If the bat house is drafty, that’s going to make it less attractive.” Fill in all of those gaps between the panels and the rails with exterior-rated painter’s caulk. If you’re planning to stain your box, which you can do if you live in a warmer climate than I do in New England, you might want to use stainable wood filler instead of caulk.  

13. Paint or finish the exterior of your box. Keeping with the theme of creating a warm house, it’s important to maximize the amount of heat absorption the box gets from the sun. That means dark colors. Bat Conservation International recommends painting bat boxes black in cold climates, but if you live in a more temperate climate, a dark brown paint or stain can be enough. If you live in a particularly warm area, you may be fine leaving the natural color of your wood.  

14. Hang the box. “This is probably one of the more important things if you actually want the bat house to work,” says Mizejewski. “Mounting is what people often get wrong, and then the box does not work.” In order to move in, bats need to feel that the box is warm enough, close to water, and safe from predators.

[Related: How to get a bat out of your house]

Oddly enough, hanging bat houses on trees doesn’t work well, even though bats often roost directly in trees. It can be too shady and cool among the branches, and it’s easier for predators to climb up and into the box. Instead, it’s best to install bat boxes on the side of a building or on a pole, between 10 and 20 feet in the air. Bat Conservation International has put together a few documents for the best installation methods, whether on a pole or on the side of your house or another building.

The post Benefit your neighborhood bats with this DIY bat house appeared first on Popular Science.

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This article was originally featured on KHN.

More than four dozen Jamaican fruit bats destined for a lab in Bozeman, Montana, are set to become part of an experiment with an ambitious goal: predicting the next global pandemic.

Bats worldwide are primary vectors for virus transmission from animals to humans. Those viruses often are harmless to bats but can be deadly to humans. Horseshoe bats in China, for example, are cited as a likely cause of the covid-19 outbreak. And researchers believe pressure put on bats by climate change and encroachment from human development have increased the frequency of viruses jumping from bats to people, causing what are known as zoonotic diseases.

“Spillover events are the result of a cascade of stressors — bat habitat is cleared, climate becomes more extreme, bats move into human areas to find food,” said Raina Plowright, a disease ecologist and co-author of a recent paper in the journal Nature and another in Ecology Letters on the role of ecological changes in disease.

That’s why Montana State University immunologist Agnieszka Rynda-Apple plans to bring the Jamaican fruit bats to Bozeman this winter to start a breeding colony and accelerate her lab’s work as part of a team of 70 researchers in seven countries. The group, called BatOneHealth — founded by Plowright — hopes to find ways to predict where the next deadly virus might make the leap from bats to people.

“We’re collaborating on the question of why bats are such a fantastic vector,” said Rynda-Apple. “We’re trying to understand what is it about their immune systems that makes them retain the virus, and what is the situation in which they shed the virus.”

To study the role of nutritional stress, researchers create different diets for them, she said, “and infect them with the influenza virus and then study how much virus they are shedding, the length of the viral shedding, and their antiviral response.”

While she and her colleagues have already been doing these kinds of experiments, breeding bats will allow them to expand the research.

It’s a painstaking effort to thoroughly understand how environmental change contributes to nutritional stress and to better predict spillover. “If we can really understand all the pieces of the puzzle, that gives us tools to go back in and think about eco-counter measures that we can put in place that will break the cycle of spillovers,” said Andrew Hoegh, an assistant professor of statistics at MSU who is creating models for possible spillover scenarios.

The small team of researchers at MSU works with a researcher at the National Institutes of Health’s Rocky Mountain Laboratories in Hamilton, Montana.

The recent papers published in Nature and Ecology Letters focus on the Hendra virus in Australia, which is where Plowright was born. Hendra is a respiratory virus that causes flu-like symptoms and spreads from bats to horses, and then can be passed on to people who treat the horses. It is deadly, with a mortality rate of 75% in horses. Of the seven people known to have been infected, four died.

The question that propelled Plowright’s work is why Hendra began to show up in horses and people in the 1990s, even though bats have likely hosted the virus for eons. The research demonstrates that the reason is environmental change.

Plowright began her bat research in 2006. In samples taken from Australian bats called flying foxes, she and her colleagues rarely detected the virus. After Tropical Cyclone Larry off the coast of the Northern Territory wiped out the bats’ food source in 2005-06, hundreds of thousands of the animals simply disappeared. However, they found one small population of weak and starving bats loaded with the Hendra virus. That led Plowright to focus on nutritional stress as a key player in spillover.

She and her collaborators scoured 25 years of data on habitat loss, spillover, and climate and discovered a link between the loss of food sources caused by environmental change and high viral loads in food-stressed bats.

In the year after an El Niño climate pattern, with its high temperatures — occurring every few years — many eucalyptus trees don’t produce the flowers with nectar the bats need. And human encroachment on other habitats, from farms to urban development, has eliminated alternative food sources. And so the bats tend to move into urban areas with substandard fig, mango, and other trees, and, stressed, shed virus. When the bats excrete urine and feces, horses inhale it while sniffing the ground.

The researchers hope their work with Hendra-infected bats will illustrate a universal principle: how the destruction and alteration of nature can increase the likelihood that deadly pathogens will spill over from wild animals to humans.

The three most likely sources of spillover are bats, mammals, and arthropods, especially ticks. Some 60% of emerging infectious diseases that infect humans come from animals, and about two-thirds of those come from wild animals.

The idea that deforestation and human encroachment into wild land fuels pandemics is not new. For example, experts believe that HIV, which causes AIDS, first infected humans when people ate chimpanzees in central Africa. A Malaysian outbreak in late 1998 and early 1999 of the bat-borne Nipah virus spread from bats to pigs. The pigs amplified it, and it spread to humans, infecting 276 people and killing 106 in that outbreak. Now emerging is the connection to stress brought on by environmental changes.

One critical piece of this complex puzzle is bat immune systems. The Jamaican fruit bats kept at MSU will help researchers learn more about the effects of nutritional stress on their viral load.

Vincent Munster, chief of the virus ecology unit of Rocky Mountain Laboratories and a member of BatOneHealth, is also looking at different species of bats to better understand the ecology of spillover. “There are 1,400 different bat species and there are very significant differences between bats who harbor coronaviruses and bats who harbor Ebola virus,” said Munster. “And bats who live with hundreds of thousands together versus bats who are relatively solitary.”

Meanwhile, Plowright’s husband, Gary Tabor, is president of the Center for Large Landscape Conservation, a nonprofit that applies ecology of disease research to protect wildlife habitat — in part, to assure that wildlife is adequately nourished and to guard against virus spillover.

“Habitat fragmentation is a planetary health issue that is not being sufficiently addressed, given the world continues to experience unprecedented levels of land clearing,” said Tabor.

As the ability to predict outbreaks improves, other strategies become possible. Models that can predict where the Hendra virus could spill over could lead to vaccination for horses in those areas.

Another possible solution is the set of “eco-counter measures” Hoegh referred to — such as large-scale planting of flowering eucalyptus trees so flying foxes won’t be forced to seek nectar in developed areas.

“Right now, the world is focused on how we can stop the next pandemic,” said Plowright. “Unfortunately, preserving or restoring nature is rarely part of the discussion.”

KHN (Kaiser Health News) is a national newsroom that produces in-depth journalism about health issues. Together with Policy Analysis and Polling, KHN is one of the three major operating programs at KFF (Kaiser Family Foundation). KFF is an endowed nonprofit organization providing information on health issues to the nation.

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Echolocation is an immense benefit for bats—and certain superheroes. Typically, the sense works via the brain interpreting sound waves bouncing off nearby surroundings to estimate information such as size and distance. Users of echolocation usually generate the sounds themselves via high-pitched clicks and pings, as is the case with bat, dolphins, and whales.

Now, researchers working at Switzerland’s Ecole Polytechnique Fédérale de Lausanne (EPFL) recently extended the sensory ability to the field of robotics, with some very promising results. As first detailed in the journal, Robotics and Automation Letters, and subsequently highlighted on Thursday by New Scientist, Frederike Dümbgen—now at the University of Toronto—and her team managed to combine a simple, cheap microphone and speaker array for both wheeled and flying robots.

[Related: When wind turbines kill bats and birds, these scientists want the carcasses.]

The cost-effective system essentially works exactly like bats’ sensory organs by first emitting short pings across a range of frequencies, then using the robot’s onboard microphone to record the sounds after bouncing off nearby walls. An algorithm designed by Dümbgen’s team next analyzes how the sound waves interfere with its own echoes, and subsequently reconstructs the rough dimensions of the room.

According to their results, a stationary robot about the size of a tennis ball could map within two centimeters’ accuracy when placed half a meter away from a wall, while the flying drone could manage within eight meters. This is a relatively far cry from the accuracy of advanced camera and laser options, but a solid alternative for its comparative light weight and cost.

[Related: How humans can echolocate like bats.]

Yet using just this basic robotic echolocation system could soon show immense promise in difficult-to-map or completely foreign environments, as well as search-and-rescue operations, as New Scientist offers. Its ability to already attach to off-the-shelf robot models—in this case, a Crazyflie and an e-puck—also makes it incredibly versatile for additional designs. For future iterations, Dümbgen’s team hopes to hone the system’s accuracy, as well as potentially phase out audible pinging setup to instead just measure inherent sound such as the flying robot’s own propellers.

Correction 2/7/23: A previous version of this article misattributed the research as taking place at the University of Toronto. Dümbgen’s research was conducted at Switzerland’s Ecole Polytechnique Fédérale de Lausanne.

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Greetings, panicking homeowner! If you’ve found this article through a frantic web search, there may be a fuzzy visitor flying around your head right now. Fear not: bats get a bad rap, but they’re nothing to freak out about. Most are totally harmless, and we guarantee they’re no more pleased with this situation than you are. It’s time to escort your spooky houseguest back outside where it belongs.

1. Don’t panic

When an unexpected creature is flying around your living space, you might be tempted to grab a rolled-up newspaper and start swatting. Resist that urge. While a flying bat may call to mind a giant insect or a furious bird, this nocturnal mammal isn’t out to hurt you. Bats won’t attack you unless provoked, they won’t fly toward you and get caught in your hair, and, no, they are not out to drink your blood. If it helps, think of your visitor as a hamster with wings: cute, furry, and ultimately powerless against a big, strong human. A bat is way more afraid of you than you are of it, so keep calm and get to work helping it find its way back outside.

[Related: Bats’ echolocation has one major blind spot]

After donning your bat-catchin’ suit, wait for your bat to land somewhere. It will likely hang high on your curtains or in another secluded location off the ground. Always wait until a bat is stationary before trying to catch it: grabbing one mid-flight is likely to injure it, and may lead to a retaliatory bite. First, try offering it a perch to hang from by resting the handle of a broom against wherever it’s hanging. The bat may climb aboard and be ready for a ride outdoors. In this case, slowly carry the broom outside or simply stick the bat-laden handle out an open window.

If this trick doesn’t work, you’ll have to consider trapping the bat in a more hands-on fashion. Move closer and quickly—but gently—put your plastic container over the animal. Carefully slide the piece of cardboard over the container’s opening to trap the bat inside, then bring it outdoors. If you don’t have a plastic container, a cloth can also work: grab a bedsheet or a large scarf and cover the sedentary bat with it, then gently bundle it up and transport it outside. Try not to use a towel for this, as bats’ tiny claws can get caught in the fabric’s loops. 

Once outdoors, release the bat onto a tree or another vertical surface where it can hang out upside down until it decides to fly away. Unlike birds, bats cannot take flight from a standing position on the ground. Offer them a high perch instead and watch until they fly away into the night.

5. Call in the experts as a last resort

If your flying guest appears injured or can’t otherwise be captured safely, the time for DIY is over and it’s time to call in the experts. Your local animal control department and wildlife rehabilitators are good places to start, but depending on the time and your location, they may not be able to arrive quickly and assist you. For rapid response, a 24-hour pest control service may be your best bet—but do a little research first to make sure they’re qualified to handle bats. 

If you or anyone else in your home has suffered a bat bite during the rescue operation, it’s a good idea to secure the bat and have it tested for rabies before releasing it back into the wild. You can do this by contacting your local health department or a veterinarian in your area. While you wait, keep the bat inside a large container. But don’t panic—fewer than 1 percent of bats actually carry rabies.

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Some species of bats are known for the ability to echolocate, or use sounds to find food. Their spooky screeches, eating habits, and fangs have also earned them historical associations with darkness, vampires, and so on. However, their eerie vocalizations could be even more unique than once believed.

A new study published yesterday in the open access journal PLOS Biology finds that bats use distinct structures located in their larynx to make high-frequency calls for echolocation and lower-frequency social calls. And to make it even more musical, the structures used to make the low-pitched calls are similar to the ones death metal singers use in their growls.

Bats that can echolocate like the greater horseshoe bat (Rhinolophus ferrumequinum) and the big brown bat (Eptesicus fuscus) have extremely large vocal range of 7 octaves, compared to only 3 to 4 octaves for most mammals—humans included. Their echolocating calls and social calls are unique among mammals at a range between 1 and 120 kilohertz.

In this study, a team from The University of Southern Denmark sought to better understand how different vocal structures allow bats to create such a wide range of calls.

[Related: The science is clear: Metal music is good for you.]

They extracted the larynx from five adult Daubenton’s bats (Myotis daubentonii) and filmed them at a speed of 250,000 frames per second, while applying air to mimic vocalization. Machine learning was then used to reconstruct the motion of vocal membranes that had been hidden by other structures in the throat.

[Related: The secret to these bats’ hunting prowess is deep within their ears.]

The air pressure crated self-sustaining vibrations in the vocal membrane at frequencies between 10 and 70 kilohertz. This amount is enough to for the bats to produce the high-frequency echolocation calls. By comparison, the ventricular folds, or the thick folds of membrane located just above the vocal cords, vibrated at frequencies between 1 and 3 kilohertz. This means they are likely the ones involved in producing the bat’s lower-frequency social calls.

Some humans actually use the ventricular folds in their throats to produce low-frequency vocalizations, such as the growls made by death metal singers and in Tuvan throat singing, a type of singing performed in Tuva, Mongolia, and Siberia.

According to the authors, this study is the first one to directly observe the self-sustained vibrations in bat vocal structures that are able to generate both echolocation and social calls.

“We show that bats vibrate extremely thin and light membranes extending from their vocal folds to make their high-frequency ultrasonic calls for echolocation,” the authors wrote in a statement. “To extend their limited lower vocal range, bats make aggressive calls with their ventricular folds—as in death metal growls.”

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The eerie air of autumn has arrived, and bats are everywhere. At the store, you’ll find decor featuring dark flying creatures with razor-sharp fangs ready to suck human blood. But outside, resting in trees and darting across the sky, you’ll see the real thing. 

Bats aren’t hunting humans or practicing Dracula impressions—they’re just hanging upside down, keeping their fur clean, and saving the world billions of dollars in agricultural costs by hunting insects.

These creatures are vital to the function of our ecosystems, which is why this fall, you should make your outdoor spaces a better place for them, and ditch the plastic blood-sucking decor for the real deal. You’ll be showing your appreciation for everything bats do, while also scaring the socks off the kids in your neighborhood—it’s a win-win.

Kristen Lear, conservationist and manager at Bat Conservation International, an organization that aims to end the extinction of bat species worldwide, explains that we should treat bats just like any other wild animal out there, and be aware of the dangers they pose as such.

[Related: Tricolored bats are imperiled by deadly fungal disease]

“You don’t want to go cuddle a bat, just like you wouldn’t go up to a wild fox and cuddle it. If we respect the boundaries that we have, we can all live together perfectly fine and benefit each other,” says Lear.

Respecting their habitat allows bats to thrive and play their role in our local environments, which includes helping with insect population control, producing one of the world’s best fertilizers, and in some cases, pollinating plants. 

And if that’s not enough to celebrate bats, keep in mind that they’re also incredible echolocators, the fastest animal flyers in the world, invaluable assets to tequila production, and very smart. 

“Way smarter than they should be for the size of their brain,” says Cory Holliday, a conservation biologist for the Nature Conservancy, a global environmental non-profit. 

Unfortunately, bats are dying, and they’re doing so at tremendous rates. Fear mongering has driven people to take on these flying mammals in great numbers, while the hibernation-disrupting  white-nose syndrome has wiped out 90 percent of some bat species in the United States. And then there’s habitat loss—the biggest threat to bats worldwide. 

Bats deserve a lot more respect and care than we give them. If you want to revert that, here’s what you can do to help while getting some spooky cred just in time for Halloween. 

“[These gardens] create shared landscapes of native organisms from every level: bacteria, fungus, insects, plants, up to vertebrates like bats and birds,” says Holliday. “They are the foundation that’s going to support that diversity that we take for granted in the United States.”

And if you want to take it up a notch, Lear says night-blooming natives are even better. The flowers in these so-called moon gardens will attract nocturnal insects, creating a late-night buffet for hungry bats.

To find plants native to your area, you can visit your local plant nursery, conservancies, and botanical gardens. Those places are usually filled with specialized people who can answer your questions and give you ideas for your own backyard. You can also use online databases like the Lady Bird Johnson Wildflower Center, or the National Wildlife Federation.

And even in cases where they are not fatal, a 2019 study published in the Brazilian Journal of Biology found that pesticides can negatively affect a bat’s reproductive system, decrease energy levels, and disrupt hibernation patterns. The latter is especially bad as it exacerbates the harm caused by white-nose syndrome.

But with bats around, you don’t have to worry as much about insect mitigation: they’re an efficient and natural way to reduce pest insects, eating thousands of them each night. Plus, you’ll be able to foster a healthier environment for you, your plants, and also bats by curtailing your chemical pesticide use.

A general rule, Lear says, is to “keep things as natural as possible,” including leaving these trees to home wildlife until they eventually fall and decompose on the ground. When that happens, bats can continue to feast on insects that take up residence in the decaying wood.

“Bat houses can be a really great benefit. They’re not only good, optimal habitat, but they’re reliable, and bats can come back year after year,” says Holliday.

You can buy bat houses or build your own at home, but just as with your own place, location is paramount. You’ll need to install the bat house 12 to 20 feet above the ground and allow it to have 20 to 30 feet of flying room around it. And even in the warmest climates, you’ll need to make sure it receives at least six hours of direct sun daily, preferably at least 10 hours in higher latitudes. Bonus points if you can find a spot with all these features that is also close to a body of water, ideally at a place with enough room to swiftly swoop down for a drink without running into something—a pond or a long trough will do. After all, if you traveled miles every night just to get a snack, you’d probably be a bit thirsty, too.

Because excess heat inside their box can result in bats dying, one of the keys to bat house success is temperature regulation. Southward orientation will ensure the enclave doesn’t get too much direct sunlight, and the proper color (depending on your location) will help with temperature balance—in general, avoid dark colors, as they retain heat for longer. Bat Conservation International has a detailed handbook on proper bat house parameters, as well as several free floor plans.

To make bat houses even more attractive, Lear says you can plant native night bloomers directly below them. As the bats poop from above, they will fertilize the plants and create a mutually beneficial system of fertilization and growth. If you have pets, you can also put a small fence around this garden to keep dogs and cats from preying on your new backyard friends.

“It’s not worth it to keep lights on just because insects can be attracted to them. If you think about the natural ecosystem, what’s naturally out there? Lamps are not,” says Lear. 

Following the rule of thumb of remaining as natural as possible, turning off outdoor lights at night helps keep bats safe and have undisrupted hunting patterns.

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In 2013, a toddler was playing under a hollow tree in rural Guinea that happened to be occupied by bats carrying Ebola. The boy contracted the disease and died, becoming patient zero in an epidemic that killed close to 10,000 people. In 2003, a betacoronavirus, SARS, managed to hop from bats in China’s Yunnan Province to the city of Guangzhou. And to the best of our knowledge, sometime in 2019, a bat gave a different betacoronavirus to a wild mammal, which ended up in a market in Wuhan, setting off the COVID-19 pandemic.

Epidemiologists have focused a huge amount of attention on hunting down the moment those viruses made the interspecies leap. Which bats? When? But there’s another, broader question to be asked: Why do certain mammals bump into each other at all? And are there forces that make it more likely that a diseased bat ends up in a place where it can infect people?

In research published last week in the journal Nature, an international team of disease ecologists found that as climate change reshuffles the habitat of mammals, it will make them much more likely to swap viruses. Hotspots for such “first encounters” are disproportionately concentrated in places with lots of people, making it inevitable that some of those viruses will end up in humans.

The research is the latest attempt to link the global process of climate change to the ways it will play out in our daily lives—not just in weather disasters, but in infant mortality, crop health, and disease. “Certainly as we’re starting to get little bits of funding in climate change and health, we’re understanding that the breadth and depth of what we’re facing are even larger than what we’ve been saying,” says Kristie Ebi, who studies climate and human health at the University of Washington.

As the study showed, we’re already living at the peak of that great shuffle; animals are migrating towards cooler temperatures right now. So it’s plausible that viral-spillover events that have occurred in our lifetimes are the result of climate change—we just don’t know which ones.

[Related: We already know how to keep the next pandemic from catching us off guard]

The conclusions are based on three years of work on a global simulation of the habitats mammals depend on and the viruses they carry. The team began with a map of the habitats of almost 4,000 mammal species, and used it to predict how those ranges would change over time given different climate change scenarios. They then looked for spots where previously isolated species would become neighbors—what they called “first encounters.” Finally, they used a recently developed computer model to predict how likely those animals were to swap viruses.

Although every mammal in the simulation eventually bumped into a new neighbor, there will be hotspots for disease spillover. The bulk will occur in tropical mountains—particularly the highlands of East Africa and Southeast Asia—rather than around the poles. That’s because as species move northward, they tend to do so in lockstep with their current neighbors. But in mountains, animals from every valley and swamp in a region will head up into ever-tighter bands of habitable elevation. That means the already biodiverse tropics will see additional species packing themselves into highlands.

Those migrants will bring pathogens. At least 10,000 zoonotic viruses already thrive in mammalian hosts; as their hosts chase cool temperatures to higher altitudes, they’ll rub shoulders with new neighbors. A species of bat that had once lived in isolated limestone caves in the jungle lowlands might now occupy a mountain slope with other wild refugees. And that could create a fresh network for transmission.

According to the Nature study, bats will spread the majority of interspecies viruses for a simple reason: They fly and can range further in search of comfortable temperatures. Rodents could be a major reservoir as well.

The model shows that the ripest conditions for spillover extend from 2011 to 2040 as animals adjust to current warming. And even under relatively moderate warming scenarios, like the 2 degrees Celsius in the Paris agreement, these spillovers will continue.

So has climate change already caused diseases to leap hosts? The field of climate attribution science, which tries to link real-world events to human-caused global warming, has blossomed over the past decade. But most of its work has focused on the weather—a few days after a “heat dome” melted power lines and killed dozens across the Pacific Northwest last year, climatologists established that atmospheric shifts were almost certainly responsible.

Attributing disease outbreaks to climate change is much more challenging. Most of the existing research has focused on diseases spread by insects, like plague, malaria, or dengue. To do so, epidemiologists need to understand how both changing rainfall and heat shape mosquito colonies, says Ebi. And just because a mosquito exists somewhere doesn’t mean it will transmit disease in that place. “You have to take all this into account when doing these kinds of analyses, which makes them much more complicated than talking about how many people are dying in a heat wave,” Ebi says.

It’s easiest to see the fingerprints of climate change in rare diseases, Ebi says. The spread of ticks and their diseases into southern Canada is a clear example. “There wasn’t Lyme disease in Canada a couple of decades ago,” she explains. “There is today.”

The new Nature paper similarly looks for cases on the fringe that are attributable to climate. In a recent event, a team of veterinary epidemiologists found that a distemper virus spread from Atlantic seals to Pacific sea otters after Arctic sea ice melted and the two mammals were able to mingle. And as flying foxes in Australia moved south over the last century, they apparently passed the zoonotic Hendra virus on to domestic horses.

[Related: The animal kingdom is full of coronaviruses. Here’s what that means for COVID’s future.]

Other climate-driven epidemics will be harder to spot—maybe animals will cross paths more, rather than meeting for the first time. The team called its simulation “ICEBERG,” as in, these first encounters are just the tip of the problem. And while the authors don’t outright connect the recent Ebola and SARS epidemics to the climate crisis, they do point out that the spillovers are probably the result of a combination of human forces, like deforestation and urbanization, that have put people in closer contact with wild animals.

What makes this kind of attribution even harder is that unlike heat waves, the world is unlikely to see spillovers as they occur. One reason that researchers have focused on insect-borne diseases, says Ebi, is that there’s money available to understand mosquitoes. “That obviously has consequences for what you study, because there’s so little funding available,” she explains. “It doesn’t mean that what we’re researching at the moment isn’t a high priority—but it is where you’re able to get some funding out of federal agencies.”

In a hearing before Congress the day the Nature paper released, one of its lead authors, Colin Carlson, a disease ecologist at Georgetown University, asked lawmakers to invest in systems for monitoring zoonotic pathogens and centralizing the information. “Our field is currently headed into something of a scientific revolution,” he said. “That vision offers renewed hope the COVID-19 pandemic could, in fact, be the last one.”

The study should serve as a wake-up call: We can see exactly how warming and habitat loss will introduce us to thousands of new viruses. Soon, we might be able to tell which outbreaks were caused by climate change itself. But either way, we can get ahead of the problem if we choose a well-informed path.

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Vampire bats are pretty unusual creatures, even by bat standards. 

They’re the only mammals to dine exclusively on blood, which means their bodies have needed to adapt in many ways to this challenging diet. Vampire bats also boast very advanced social skills, says Michael Hiller, a professor of comparative genomics at the LOEWE Centre for Translational Biodiversity Genomics in Frankfurt, Germany. 

Hiller and his collaborators are investigating the genetic changes that have enabled vampire bats to thrive. They analyzed the genomes of common vampire bats and more than two dozen other bats, and have identified 10 genes that are no longer functional in the vampires. Several of these alterations may help the bats cope with the high iron levels in blood and contribute to their impressive cognitive abilities, the team reported on March 25 in Science Advances.

“These gene losses tell us a lot about past natural selection in the vampire bat lineage,” Gerald Carter, a behavioral ecologist at Ohio State University who wasn’t involved in the new research, said in an email. “These traits are not just about how they digest blood. It extends out to how they behave and even how they think.”

Blood is a “suboptimal” food source because it’s nearly 80 percent fluid, while the rest is largely made of protein, with very few fats and sugars, Hiller says. Since blood is so low in calories, vampire bats must slurp down as much as 1.4 times their body weight in a single meal.

Among their other specializations, vampire bats have infrared sensors around their noses, razor-sharp and enamel-less incisors to slice through their unsuspecting dinner’s skin, and anticoagulants in their saliva to keep the blood flowing while they feast. They’re also adept at sneaking up on prey by hopping along on their elbows and can even run and jump. “They have pretty exceptional terrestrial locomotion skills, while in other bats it’s much more limited,” Hiller says. 

[Related: Female vampire bats regurgitate bloody dinners for their starving girlfriends]

Because of their low-nutrient diet, vampire bats are very vulnerable to starvation. Sated bats regularly share regurgitated blood with neighbors who failed to obtain their nightly meal. “The decision with whom to share blood is primarily driven by who was helping you out in the past,” Hiller says. This means that vampire bats can recognize their roost mates and remember their past actions. They also form lasting social bonds; Carter and his colleagues have observed that captive bats will stick together even after they’ve been released.

In order to support their sanguivorous lifestyle, Hiller says, vampire bats have likely tweaked their genetic instructions in various ways. His team focused on genes with mutations that destroy their ability to encode working proteins. Often, such genes are inactivated because they’re no longer useful for the animal, while in other cases losing a gene can actually provide a survival advantage. 

To understand how these processes might have played out in vampire bats, the researchers sequenced the genome of one of the three known species. They then compared it to published genomes of 26 other bats, searching for genes that were missing in the blood-suckers but present in their closest and more distant relatives. 

“We were asking, using this new genome, which genes were specifically inactivated along that branch leading to the common vampire bat,” Hiller says. He and his colleagues pinpointed 13 gene losses in vampire bats that seem to be related to their distinctive traits. 

Three had been reported previously and were linked to sweet and bitter taste perception, indicating that vampires have a poor sense of taste. “If you only feed on blood from a live animal, you don’t have to worry about the meaning of new flavors or your food being spoiled,” Carter noted.

Similarly, among the 10 newly-discovered gene losses, Hiller says, “We think the simplest explanation for many of them is likely what people describe as ‘use it or lose it.’” 

Vampire bats get barely any sugars and fats from their meals, so several genes involved in processing these nutrients were perhaps no longer needed. Nor was a gene related to stomach acid secretion. “Their stomach has been converted from a digestive organ that secretes acid, like us and other bats, to a distensible storage organ,” Hiller says. Vampires prefer to hunt in the darkest hours of night—they even avoid moonlight—so genes necessary for color vision were probably also rendered obsolete. 

[Related: Vampire bats socially distance when they feel sick]

Other genes played roles in digesting proteins and combating potentially dangerous microbes, but it’s unclear why they were inactivated. One possibility is that the immune-related gene lost its importance because the pathogens present in blood are so different from those in other tissues of the prey animals’ other tissues, Hiller says.

Most exciting, he says, were two cases where ditching a particular gene seems to have directly helped vampire bats adapt to their “very specific” lifestyle. 

Vampire bats consume up to 800 times the amount of iron that humans do, which can have dangerous consequences. However, the researchers identified a gene loss that allows the short-lived intestinal cells to soak up more of the mineral before they’re shed into the gut and pooped out. This could keep the bats’ iron levels in check.

The other inactivated gene codes for an enzyme that normally breaks down a molecule produced from cholesterol. That molecule stimulates parts of the brain involved in learning, memory, and social behavior. In the future, the researchers plan to measure whether losing the enzyme has given common vampire bats elevated levels of the cholesterol-based molecule, which might underlie some of their social habits. 

The team has also recently sequenced the genomes of the two remaining vampire bat species and will compare all three sets of genetic instructions in detail. And, while the new findings highlight how gene loss can be an important evolutionary mechanism, Hiller says, it’s not the whole story. 

“Gene loss is only one kind of genomic change,” he says. “With the new genomes we have, we would now like to run more comprehensive screens to better understand the underpinnings to these adaptations.”

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Bats are masters at detecting sound—and a lot of it has to do with the mechanics and structure of those adorably large ears. A set of unique inner ear features may explain how one group of bats evolved the sophisticated echolocation strategies that have allowed them to thrive on every continent except Antarctica, scientists report today in Nature.

The researchers examined the skulls of 39 bat species from two major groups called Yinpterochiroptera and Yangochiroptera. They discovered that the yangochiropterans, which includes most bat families and 82 percent of echolocating species, have inner ears unlike those of any other mammal. These bats have inner ears with extra space inside the cochlea and more neurons, which may help them hunt within a broad range of environments. 

“We posit that it enables the really complicated echolocation calls that the yangochiropteran bats are famous for,” says Bruce Patterson, a curator of mammals at the Field Museum of Natural History in Chicago and coauthor of the findings.

Bats were traditionally divided into two groups called Megachiroptera and Microchiroptera, or megabats and microbats. Megachiroptera included the flying foxes, which generally find fruit and nectar by sight and smell, although a few also use tongue clicks as echolocation signals. Microchiroptera encompass the bats that have a type of echolocation that uses sounds produced in the larynx, known as  laryngeal echolocation. Microbats mostly eat insects, including agricultural pests, and other small animals. 

However, since 2000, genetic evidence has indicated that some of these echolocaters are actually more closely related to megabats than to other microbats. This led researchers to propose two new groups. Yinpterochiropterans dwell in the Eastern Hemisphere and include flying foxes as well as a few other families such as the horseshoe and mouse-tailed bats. By contrast, the 938 yangochiropteran species are found around the world. Their ranks include the free-tailed bats, vampire bats, ghost-faced bats, the big brown bat, and the ever-popular charismatic Honduran white bat.

[Related: How humans can echolocate like bats]

The wide array of adaptations found among these bats have stymied scientists searching for anatomical traits that could differentiate yangochiropterans from yinpterochiropterans. “Most of the diversity is in the yangochiropterans,” Patterson says. “So finding something that tied them all together was like a needle in a haystack, but this inner ear character suite seems to be exactly that.”

He and his collaborators investigated skulls from 19 of the 21 families of living bats. The team used CT scanning to peer inside the tiny skulls and examined fine cross sections of the inner ear structures under the microscope. 

Since the Jurassic Period, mammals have had a distinctive arrangement of inner ear structures within the snail shell-shaped cochlea. A cluster of neuron cell bodies called a ganglion transmits nerve impulses received by hair cells to the brain. The ganglion is contained in a thick bony wall perforated by tiny pores that allow nerve fibers to pass through.

But in yangochiropterans, the setup looks a bit different. “As you ascend this spiral, the wall opens up,” Patterson says. In some bats, the tiny pores become “much bigger windows” that allow large nerve bundles to pass through. Eventually, Patterson says, “the wall just disappears and the ganglion actually flops out of the canal.” In other yangochiropterans, the bony wall is absent throughout the length of the ganglion canal. As a result, the bats can pack in more neurons to receive incoming auditory signals.

What this suggests, Patterson says, is that “it was the greater freedom from constraints of the bony canal, the larger size of the ganglion, and the more intimate bundling of [nerve fibers] that was responsible for the explosive diversification of the yangochiropteran bats.”

Among yinpterochiropterans, the species that echolocate emit a barrage of sound pulses at a constant frequency. This kind of echolocation is great for finding insects scampering over leaves and other clutter but isn’t much help for open-air hunting, Patterson says. Yangochiropteran bats utter echolocation calls at longer intervals that start off high before swooping down to lower frequencies. These cries effectively give the flying mammals a more powerful “flashlight beam” that can travel farther and can gather more diverse information about their surroundings. 

The strategy could be adapted for a broader range of conditions. It “represented kind of an adaptive breakthrough for bats because it gave them mastery of the night skies and freed them from focusing on bushes,” Patterson says.

[Related: Bat echolocation could help us understand ADHD]

The findings indicate that the walled canals characteristic of yinpterochiropteran bats transitioned over time to create the unique inner ear architecture of yangochiropterans, M. Brock Fenton, a biologist at Western University in London, Ontario, wrote in a short review published in the same issue of Nature. This supports the idea that echolocation emerged before this split, and the skill was later lost in some yinpterochiropterans.

“This is an exciting new mammalian character identified in bats that can be used to shed new light on how laryngeal echolocation has evolved in mammals, addressing a long-standing evolutionary debate,” Emma Teeling, a professor and bat biologist at University College Dublin who wasn’t involved in the research, wrote in an email.

Intriguingly, the researchers identified two yangochiropteran bats that, unlike their close relatives, had a thick bony wall running the entire length of the cochlea. It’s not clear why this evolutionary reversal took place, although Patterson suspects it’s related to the bats’ highly specialized hunting strategy, which involves skimming the water’s surface and grabbing small fish or insects with their feet.

This observation highlights the fact that many questions about how echolocation has evolved in both bat groups remain to be investigated, he says. 

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Did your school dining hall offer a universally beloved dish? One that attracted long, meandering lines, one that people would immediately line up for without finding a table? (At my school it was hash brown triangles and sweet potato fries.) Maybe you couldn’t possibly get there early enough to get yourself a plate—so a contingency plan was to pray you’d run into a friend who was already in line—and then you could share with them.

This may seem like a uniquely human experience, but there’s evidence that a similar behavior is fairly common among vampire bats. A recent study published in the journal PLoS Biology found that on foraging trips away from home, these bloodsuckers tend to meet up with roost mates they share close bonds with. The observed bats didn’t leave to go foraging together, but if a latecomer ran into a friend already slurping on a cow, that friend was likely to scoot over and share its tasty spigot. On the other hand, if the bats didn’t already share bonds, then nobody asked to pull up a seat, and one would continue on its merry way.

“What this showed us is that these are really bonds,” says Gerald Carter, one of the study’s authors. “Even if you put them in a totally different social environment, they’re still with each other,” says Carter, who works as a behavioral ecologist at The Ohio State University.

Two bats, both alike in dignity

Vampire bats are easy enough to describe: tawny, snub-nosed creatures that look a little like mice with pug faces, cat ears, and delicate, translucent wings. Although they can have a wingspan up to seven inches, when folded up, the tiny creatures can fit inside teacups. Chiropteran social behavior, though, has until recently remained mostly a mystery. 

Carter knew from previous research that females sometimes form tight social bonds that involve grooming one another, but also go as far as sharing regurgitated blood leftovers. Male vampire bats tend to fight more over territory, and do less grooming and food sharing. But that female bonding behavior had only been observed in roosts. This time, Carter’s team wanted to know if that generosity held up in the feasting fields.

To figure it out, Carter and his colleagues looked at two groups of female vampire bats living in the wild in Panama. They decided to focus on females because they tend to have stable social relationships, as opposed to more combative males. 

One group included 27 wild females that were caught, tagged, and released. The other group comprised 23 females that had spent 21 months in captivity and were then released back into the wild. This distinction is important: Keeping the bats in captivity allowed Carter to closely observe the relationships within the group. He learned which bats groomed and ate together, and gained a solid understanding of their social structure. The question now was: Once the previously captive bats were released, would they choose to interact with unfamiliar bats?

Evidently not. Once those bats were out of captivity, their previous relationships persisted, with the bats tending to spend time with others they already shared bonds with. This pattern held true even in the tagged wild bats. 

“It implies that the animals have a mutual social preference for each other, which is not something you can immediately tell just from observation,” Carter says. For instance, animals in captivity may appear to be spending time together, when in reality they both just prefer the same corner of a cage or feed at the same time. But these bats leave on their own and choose to reconnect with friends they see outside the roost.

[Related: 6 surprising facts about Halloween’s mascots]

“I was surprised that they never left together,” says Carter. “None of the 50 bats that we tracked left the roost at the same time. They left minutes apart, which I didn’t expect at all.” Are the bats in a group chat making plans to meet up at the same buffet (which in this case meant the same cow)? It’s more likely, Carter says, that they use echolocation. He says his team recorded different calls the bats made to each other, including one call they had never heard in captivity or a roost, which means that “this could be a call that they specifically use when they’re out there hunting,” says Carter.

Bat buddy system

The reason for this particular style of foraging is twofold. By leaving the roost to forage individually, the bats don’t have to compete among their own colony for food. But if they do encounter bats from outside colonies while foraging, teaming up with a roost buddy already at the table, so to speak, potentially gives them a spot on a cow. Carter says vampire bats don’t have deep hierarchies, and going out in packs could breed dominance.

“They might be encountering a lot of other bats that they just don’t have any relationship with,” he says. “The fact that they could eat with another bat they do have a relationship with becomes attractive.”

[Related: Why do so many diseases come from bats?]

While bats make up one quarter of mammal species, we actually don’t know that much about them because they’re so difficult to track. Researchers know much more, for instance, about bird and primate socialization. But this study provides a rare peek into bats’ inner lives. While the finding itself is intriguing, Carter says it sets the stage for future research on bat behavior. 

His next plans entail using GPS to localize both bats and their cattle prey so he can track every bat-cow encounter in a given area. This data could be useful in tracking bats as vectors for spreading rabies to livestock or people, which is a problem in places with carnivorous bats, like Latin America.

“People think there’s nothing really interesting going on [with bats],” Carter says. “I just don’t think this is the case. I think they do have these really complex relationships, but we haven’t been able to study them.”

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The Greater Sac-winged bat, known for clinging to the sides of buildings and feasting on insects, couldn’t seem more different from a human. However, it turns out we have more in common with these three-inch-long flying mammals than meets the eye. 

According to a study published today in Science, Greater Sac-winged pups babble just like human babies. Not only do the black-furred infants burble like us, but they possibly do so for the same reason: to learn how to talk. 

In fact, these tiny critters spend about 70 percent of their infancy prattling off nonsense as a way to practice syllable formation, says lead author Ahana Aurora Fernandez, a postdoc at the Leibniz Institute for Evolution and Biodiversity Research in Berlin. By the time their three-month infancy was up, the Central American natives learned an average of 12 to 20 unique syllables—half or most of the 25 syllables adults use to form their squeaks and squeals. 

Babysitting babbling bats 

To determine if the pups’ warbling was similar to those of human tots, Fernandez spent every day for four months observing the newborns from sunrise to sunset. She watched 20 itty-bitty bats grow up across two colonies: one in Panama the other in Costa Rica. 

Fernandez and her team collected audio recordings of the squealers in addition to their observations. The researchers then analyzed the baby bat songs to see if they met eight universal characteristics of human babbles including early onset, repetition, rhythmicity, universality, and occurrence in non-social settings. 

[Related: Female vampire bats regurgitate bloody dinners for their starving girlfriends.]

“We came up with this list of eight features after digging into the literature of human infant language acquisition,” says Fernandez. “We read a lot of papers and books, and also talked to many leading researchers in the field to really understand what is going on when human babies go ‘bababa’ or ‘dadada’.” 

Turns out baby bats’ burbles met all of Fernandez’s characteristics of human toddler jabbering. The pups’ babbling bouts were repetitive with 77 percent of the syllables uttered were succeeded by the same syllable type. According to Fernandez, bat baby phrases also took on a rhythmic beat just like the endearing ‘papas’ and ‘mamas’ of human infants. 

Just like human infants, the chatter of the growing bats did not require a social context. They yammered whether they were hanging alone, cuddling with their mom, or nursing. In fact, they spent 30 percent of their days testing out their vocal cords. The average prattle bout lasted about 7 minutes, with the longest being 43. In comparison, adult bats only speak for a few seconds to a few minutes at a time. 

While no individual infant managed to accrue all 25 syllables used by adults, each of the 20 pups learned the 10 syllables from adult males’ territorial and mating songs. This shows that bats don’t babble for no reason—they’re actually learning a language. 

But unlike a human baby’s cries or coos,  a pup’s warbling rarely elicited a caretaker’s response. When a human toddler utters ‘mama,’ their mother probably will react. However, during the course of the study, it seemed no amount of yakking induced a similar response in adult bats. 

Why we should tune into bat chit chat 

Very few mammals are known to chatter throughout their childhood. In fact, only humans and songbirds have been observed warming up their vocal cords during early development, says Fernandez. Therefore, this babbling bat discovery means scientists can now compare how two very different species learn to communicate. 

[Related: Vampire bats socially distance when they feel sick.]

“I was always interested in vocal communication because we as humans are so communicative, right? I mean human language defines human nature. We use language daily to share ideas,” says Fernandez. “So, I really wanted to understand the communicating systems of other animals because I think by learning how they communicate and perceive the world, we can learn about ourselves.” 

Fernandez hopes that future studies will conduct neurological work to watch the bats’ brains during toddler twaddle and look for similarities to brain development in human children. In the meantime, she hopes we can all appreciate bats a bit more. 

“It was just amazing to have this experience to work with wild animals,” says Fernandez. “When I’m sitting in the middle of the jungle, I feel privileged that [these bats] allow me as a human to just observe their natural behavior. That they’re so accepting of me. It’s amazing.”

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Nobody ever accused the bat of being beautiful. But its ugliest features—its freakishly ornate ears and intricately furrowed mouth—play a key part in the animal’s uncanny ability to track its prey. The mystery is how.

Robat

Now, through sophisticated computer modeling and robotics, Rolf Müller and Herbert Peremans are at last beginning to reverse-engineer a digital approximation of the bat’s ultrasonic sonar system. Their effort, part of an $8.5-million European Union project called CILIA, could lead to more-advanced sonar technology—and possibly even bat-inspired antenna designs.

All active sonar, including in the animal world, involves emitting sound pulses and interpreting the reflected echoes. But even the best man-made systems are no match for the bat, which can sort through countless noises on the fly to pinpoint obstacles or prey, a key part of a navigational process known as echolocation.

Müller, a computational physicist at Shandong University in China, has amassed what is probably the world’s largest database of bat parts—nearly 600 Spock-like ears and wrinkly facial structures called noseleaves. His specimens come from caves, attics and occasionally even restaurant kitchens across Southeast Asia.

Spocking

In his lab, Müller puts the dissected parts through a digital CT scanner, which captures details as small as 10 microns. His team designed a computer model to simulate how sound waves pass through these structures and provide clues to how the bat’s natural sonar transmitter and antennae work. So far, the scientists have learned that a protrusion in the outer ear called the tragus (in humans, it helps hold earbuds in place) appears to help the bat organize the incoming sonic clutter. Müller is meeting with a NASA scientist to investigate whether the work could improve antenna designs.

Meanwhile, Peremans, an electrical engineer at the University of Antwerp in Belgium, is busy creating a set of synthetic ears and mouths based on Müller’s 3-D scans. These will attach onto a life-size robotic bat head dubbed the “robat.” Carrying an ultrasonic transducer capable of producing bat-like 20- to 200-kilohertz pings, it will help them develop better robotic sonar and navigation systems.

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COVID-19 has been a stark reminder that when weak muscles, an unforgivable headache, and a sore throat make an appearance, we should cancel all our plans. But it turns out, we’re not the only ones in the animal kingdom that practice this public health measure. Recently published research shows that Vampire bats also isolate from their peers when they feel sick.

The team tracked 31 Vampire bats in the wild, half of which had been injected with a molecule that gave them virus-like symptoms without exposing them to any actual disease. After closely monitoring their behavior using sensors to track the animals’ movement, researchers found that “sick” bats hung out with fewer bats, spent less time near others, and were “less socially connected to more well-connected individuals.” In short, they socially isolated from their community.

“It’s basically the same when we contract the flu, and we feel miserable, and we don’t want to get out of bed,” says Simon Ripperger, leading author of the new study, which was published this week in Behavioral Ecology. “[In that situation] you’re not going to go have a beer with a friend because you just don’t feel like that. This passive social distancing is what we researched here.”

How a host behaves when they are contagious is one of the most important predictors of how quickly an infectious disease can spread. Still, it’s been challenging to answer that question in wild animals—and humans, says Dana Hawley, a biologist at Virginia Tech who didn’t participate in the research. “I found this to be a fantastic and exciting study,” she said in an email to Popular Science.

The study suggests that, at least in bats, the behavior accompanying sickness could have a social meaning. “This study helps to explain why we might feel sick when we are infected with colds and flu,” says Damien Farine, an evolutionary biologist at the University of Zurich in an email to Popular Science. Farine wasn’t involved in the current study. Our behavior when we’re sick “could be a cue for us to stay home and out of people’s way to prevent further spreading,” Farine says.

Biologists have been studying Vampire bats’ social networks for decades; their societies are among the most complex in the animal world. Previous research in labs had shown that when these bats feel sick, they interact less with their peers. Ripperger and the team at the Smithsonian Tropical Research Institute wanted to test those findings in the wild.

So, on April 24, 2018, when the last sun rays fell over Belize’s Lamani Archeological Preserve, the team put mist nets on every possible exit of a hollow tree where a colony of about a hundred Vampire bats nested. They captured 41 females, and ended up including only the 31 that didn’t figure out how to remove their sensors. They injected half of the bats with a water-based salt solution had no effect on their bodies, and the other half with lipopolysaccharide, a harmless substance that tricks the animal’s immune system into believing there’s an infection going on for a couple of hours.

Then, the team installed tiny mini-computer backpacks on each bat, which track the mammals’ trajectories and exchange information with the rest of the sensors. This allowed the team to map out in full detail how much each bat moved, how much time the animals spent with others, and how close they all got to each other. One hour after the bats had been injected and tagged, they went back to the wild.

The team monitored the interactions of the animals for three days. As expected, during the first six hours, the bats with lipopolysaccharide running through their veins moved less than the placebo recipients. During this period, “sick” bats hung out, on average, with four fewer friends than “healthy” ones. Their interactions were also shorter: They spent 25 minutes less than “healthy” bats with each partner. On average, the “healthy” bats had a 49 percent chance of associating with one another, but only a 35 percent chance of being near “sick” ones. Twenty-four hours later, the effects were much less pronounced. Two days later, the previously “sick” bats were interacting at the same rate as the rest of the group.

Figuring out how the behaviors of both sick and healthy animals dictate the emergence of a disease is an open-ended, exciting question, Virginia Tech’s Hawley said. “It seems like the bat that feels sick is essentially withdrawing from interactions, but are healthy bats also avoiding bats that “look” sick?”

For Ripperger, the data recently published can help researchers to understand, and potentially model, the spread of an actual pathogen in a community of bats. “We can run a model with this data with a pathogen that requires body contact in mind, for example,” he says. “We can use the same data set to model the spread of that pathogen because we know how close together the bats were and for how long. This is really fascinating.”

From an evolutionary standpoint, the study also poses the question of how, and why, selection has favored such individual behaviors, as these are unlikely to benefit neither the pathogen (because it reduces its ability to spread) nor the sick individual (because it already has the sickness), says Farine.

“Studying social distancing in non-human animals helps us appreciate that [this practice], which feels very unnatural and hard to us, is very much a natural strategy for social animals,” says Dana Hawley. “That doesn’t necessarily make it any easier, but helps put humans in a broader context.”

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Much about the beginning of the COVID-19 pandemic remains unclear, but it’s likely that the novel coronavirus originated in bats, perhaps then spread to another animal that in turn passed it to people.

This isn’t the first disease we’ve faced that has come from the little flying mammals. Other coronaviruses that researchers are aware of that also cause severe illnesses in people—the original SARS and Middle East Respiratory Syndrome (MERS)—have been linked to bats. A recent study found that bats and the coronavirus family have in fact been evolving together for millions of years, although it’s rare for different bat species to pass coronaviruses to each other.

Bats are natural hosts for other high-profile pathogens such as the Ebola and Nipah viruses as well. Scientists have found that bats seem to harbor a particularly large number of viruses that can infect people compared with most other animals.

So what is it about bats that causes them to carry so many of these viruses? Researchers have identified a few possible explanations—although none of them mean we should live in fear of bats or blame them for the spread of COVID-19. Just because bats harbor viruses that can infect people doesn’t mean that they’re spreading disease in their wake while flitting across the countryside every night.

Bats have some unique characteristics that might allow them to host an abundance of viruses, says Bruce Patterson, a curator of mammals at the Field Museum of Natural History in Chicago. These mammals are “extraordinarily social” and spend much of their time packed together. During the summer, the world’s largest bat colony descends on Bracken Cave in Texas, bringing more than 15 million Mexican free-tailed bats together. The pups born in this cave can roost in densities of up to 500 bats per square foot.

“We’re all learning about social distancing and its effects on breaking up viral transmission—well, that’s hard to do when your whole biology involves huddling and taking care of one another in these very…tight social groupings,” Patterson says. “It doesn’t take very long for any pathogen or parasite to make its way through the entire population.”

Because of this gregarious way of life, bats evolved powerful immune systems in order to survive, Patterson says. This robust defense allows them to carry viruses without falling ill or at least withstand deadly diseases such as rabies longer than other mammals can.

“Bats are able to keep rabies at arm’s length and actually live with it for a while, whereas a human that comes down with rabies is gone in very little time,” Patterson says.

This natural protection powers down only when bats hibernate in winter to save energy. That’s part of why the tiny mammals are so vulnerable to the fungus that causes white-nose syndrome, the disease devastating bat populations in North America, while hibernating.

In addition to having this beastly immune system, bats are also the only mammals with the ability to fly. Some of the adaptations bats have evolved to help them stay aloft could also make them resilient to viruses.

“Flying is one of the most expensive ways to get around; it’s far more costly energetically than swimming or walking or running,” Patterson says. “Bats have to really work to stay in the air and do it hour after hour through the night.”

Because bats use so much energy to fly, they have a high metabolic rate. When animals metabolize food and turn it into energy, though, this process creates byproducts called free radicals that are harmful to our DNA. Animals, including humans, have ways of preventing or repairing DNA damage, and these capabilities seem to have become particularly efficient in bats to help them cope with their whirring metabolisms, Patterson says.

When viruses infect an animal, they invade its cells and force them to build more viruses instead of copying their own genetic code into new cells. But viruses might not be able to hijack bats’ genetic machinery as effectively as they do in other mammals because bats have such excellent DNA editing and repair mechanisms.

“That same property translates into really exceptional longevity in bats,” Patterson says. A little brown bat living in your attic might survive 30 years or more, he says, while the house mouse, another mammal of similar size, has a lifespan of only two or three years.

It’s also possible that flying gives bats such an incredible workout that their bodies heat up enough to fight off viruses while on the wing. This is in some ways similar to the way a fever helps fight infection.

All of these factors combined—their super social behavior, adaptations for turbo-charged metabolisms, and elite immune systems—creates the perfect storm for harboring and transmitting diseases. “The things…that are peculiar to bats that make them pretty good at keeping viruses from overwhelming their systems also make those viruses persist in their systems longer than they do in other groups,” Patterson says. “And that increases the potential for bats to pass it along to somebody else.”

However, detecting a virus in a given animal only provides evidence that it can infect that particular species, Nardus Mollentze, a viral ecologist at the University of Glasgow, told Popular Science in an email. It doesn’t directly imply that the species in question is actually transmitting the virus to people. In fact, his team found that bats are not the most common animal to transmit infectious diseases to humans. There are other species that are just as likely.

Mollentze and his colleague Daniel Streicker, also at the University of Glasgow, recently created a database of viruses found in mammals and birds. They found that groups of closely related animals that had a lot of species within their group had more human-infecting viruses associated with them compared to groups of animals with less species. In other words: there are a lot of different bat species, so it’s not surprising that we’ve detected so many zoonotic viruses in bats.

They reported their work on April 28 in Proceedings of the Natural Academy of Sciences.

“The number of zoonotic viruses coming from bats is certainly high, but that is also true of other species rich groups such as rodents,” Mollentze said. “What our data shows is that as a group, bats do not transmit more viruses to humans than other mammalian groupings of comparable size, and are not more likely to transmit viruses to humans than any other group.”

Many species of bats are endangered and very rarely come into contact with humans, he added. In fact, a number of diseases found in bats are typically passed to people by other animals. You’re more likely to catch rabies from a skunk or raccoon than a bat, MERS is often transmitted by dromedary camels, and the SARS epidemic in 2003 probably began with captive civet cats.

To avert future pandemics, it’s essential that we discover which viruses are circulating in wild animals and could potentially infect people. That means monitoring animals that could play a role in their transmission to people, including bats.

However, there’s a lot we still don’t know about this diverse group of animals, Patterson says. In the journal ZooKeys, he and his colleagues recently reported their discovery of four new species of leaf-nosed bats, which are closely related to the family of horseshoe bats from which the novel coronavirus may have originated.

Despite the fact that bats contain and spread disease, they are still vital members of the world’s ecosystems and we are far better off with them than without them. Bats often escape our notice because they’re nocturnal and different species tend to look very similar. “They aren’t colorful [and] they don’t have beautiful songs that we can listen to and recognize the way we can with birds,” Patterson says. “Twenty-five percent of the bat species we recognize today were thought to be something else 15 years ago; that’s a shocking number.”

What we do know, however, is that bats are incredibly valuable members of their ecological communities. They gobble up insects that would otherwise feast on crops; bats are estimated to save farmers in the United States at least $3.7 billion per year in pest control services. Their hearty appetites also keep insects that transmit diseases such as West Nile Virus in check.

Nectar-drinking bats pollinate the plants they feed from; in Africa, baobab trees are mainly pollinated by fruit bats. As they fly about, bats also help plant new vegetation in tropical forests by pooping out seeds from the fruit they dine on.

“All of these things are really important ecological roles and we can’t lose track of that because of our fears and concerns about viruses associated with [bats],” Patterson says. Bats are facing threats enough from habitat loss, climate change, diseases like white-nose syndrome, and the bushmeat trade. “They’re already on the ropes because of human activities and we should do all we can to make sure we don’t further imperil them through our actions.”

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Would you let a stranger borrow your car or your favorite pair of shoes? Probably not. What about your best friend?

You’re arguably more likely to hand over your keys or your ritziest kicks to your BFF, of course. But once upon a time, the person that you adore most was also a stranger—and the road from random acquaintance to closest pal can be a long journey. Friendships always take time, as each of you slowly builds trust for one another. After all, you don’t want to lend someone your ride who wouldn’t do the same for you.

“If the other person doesn’t cooperate with you, you’re even worse off for trying to start that relationship,” says Gerald Carter, a professor of behavioral ecology at Ohio State.

This idea of slowly investing your time, energy, and supplies into a trusting friendship isn’t new. In fact, scientists coined a theory for it, called “raising the stakes.” And people aren’t the only living creatures that amass a network of complex social relationships. But it turns out the spookiest members of the animal kingdom—our dearest cave-dwelling bat friends—also slowly test the waters when it comes to getting to know a new buddy.

A new study in Current Biology authored by Carter found that wee vampire bats also “raise the stakes” when cooperating with their fellow cave mates. Early on in their friendships, these tiny mammals test the waters by grooming each other. If that works out, they move on to the species’ most coveted kinship act: sharing blood meals.

Bats might not be the first creature that comes to mind when you think of friendly critters, but these relationships are essential. Each bat needs about two tablespoons of blood to eat each night, and going a few nights without that meal could be fatal, says Brock Fenton, a bat biologist at Western University in Ontario, Canada who was not involved in the study. Being a good sharer, and a good friend is quite literally life or death.

Carter and his colleagues followed pairs and groups of previously unfamiliar female vampire bats over 15 months to record how they interacted. What they saw was a progression of friendship “investments” in the form of grooming, with the grand prize being blood sharing, which only ended up in 10 to 15 percent of the pairings.

This kind of study—following how a close friendship develops over time—has yet to be done in such a way in people, primates, or other animals that are known to have very complicated social structures.

“We understand the consequences of having close relationships,” Carter says, but “we know less about the process of building those, and how much is under the control of an individual.”

It’s tough to capture the moment when strangers become friends, animals, or humans. You have to be there at the exact right moment in the wild, which can take years of observation. But viewing friendly relationships in captivity is tricky too. You never can be completely sure what you’re watching isn’t an acquired skill you trained a critter to do.

That’s why vampire bats make the perfect subject for this kind of study, Carter says. You can recreate their natural home, a lot of times, a dark tree trunk the size of a closet, quite easily in a lab setting, and you don’t have to train them to do anything.

The wildest part—these creatures who shared their bloody snacks still remained friends when they were released into the wild, Carter says. With the help of tracking devices, the researchers could see the “bat besties” meeting up again outside of captivity, even if the wild population had a much larger group of potential buddies to choose from. These collaborative relationships weren’t just for survival in captivity, he says, but are really lasting friendships.

Fenton says that this kind of research puts bats in a new perspective as incredibly cognizant creatures, alongside primates, whales, elephants, and humans.

“They know what they are doing. They know each other,” he says. “Those are all things that used to be our domain.”

So while bats might give you mental images of Halloween or spooky caves, in reality, they are critters who, just like us, carefully curate their ride-or-die squads.

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For more than a decade, bats in North America have faced a devastating crisis as white-nose syndrome has swept across the eastern United States and Canada. The fungal disease has felled millions of these tiny mammals since its first documented appearance in New York in 2006. Scientists believe the fungal culprit, known as Pseudogymnoascus destructans, was accidentally introduced from Europe—yet it has mysteriously spared bat populations in Europe and Asia.

Researchers think part of the reason that Eurasian bats weren’t as stricken by the disease was that their immune systems were simply used to the fungus, but now they think they’ve landed on another potential explanation: The roosts, or homes, where North American bats hibernate over winter are P. destructans hotbeds; each year when they return, they are likely getting reinfected with the deadly fungus. The researchers reported their findings this week in Proceedings of the National Academy of Sciences.

“They’re becoming infected almost immediately upon returning to that contaminated environment,” says coauthor Joseph R. Hoyt, a disease ecologist at Virginia Tech in Blacksburg. “Whereas the pathogen doesn’t build up in the same way in Europe and Asia—it appears to be decaying over the summer.” We might be able to protect bats in North America by getting rid of the excess fungus in their winter haunts, he says.

To find out how white-nose syndrome was affecting bats on different continents, Hoyt and his colleagues visited 101 winter roosts around the globe over a period of 8 years. In both early and late winter, they counted how many bats were present, and took swabs from the hibernating animals and the walls and ceilings of their living areas. The team found that P. destructans was much more prevalent in North American roosts at the beginning of winter than in European or Asian roosts. At some North American sites, nearly all the bats were infected not long after they’d settled down to hibernate. These mammals also had more serious fungal infections than their European and Asian counterparts. In the most fungus-ridden areas, bats succumbed to the infection at a far higher rate as well.

Bats are only vulnerable to white-nose syndrome in winter. The fungus thrives in cold conditions and to make matters worse, during the colder months the mammals cool their bodies down to save energy while food is scarce. This makes them perfect targets for the fungus. White-nose syndrome causes bats to become restless and move around more than they should during hibernation, burning up precious fat reserves. However, the disease is not always fatal. If a bat can hang on until spring, it’s warmer body and more active immune system will fight off the fungus after it wakes up.

In both Eurasian and North American roosts, the fungus becomes more plentiful as winter drags on. But the Eurasian bats typically weren’t infected until later in the season, giving them a better shot at surviving until spring.

Many bats do wake themselves up every few weeks during the winter to groom or mate. So the more fungus is present in its winter abode, the likelier a bat is to eventually make contact with an infected surface or fellow bat during these activities.

Over the summer, the amount of fungus in the Eurasian roosts dropped. The researchers suspect other species of fungus take over or other microbes eat the P. destructans. In North America, however, it has no natural enemies and can run rampant.

“It’s basically like the environment is reset each year,” Hoyt says. “It’s not that there is no fungus present…but because it’s been so greatly reduced, bats come in and are not immediately infected.”

Hoyt and his team hope to recreate this effect in North America by spraying disinfectants during the summer into the bats’ abandoned winter homes to bring the fungus down to manageable levels. “We can look at the relationship between how much pathogen is present in the environment and then at what point do we see stabilization in populations,” he says. “That would be the target.”

Caves are home to unique and fragile communities of microbes. However, many bats actually roost in less pristine digs, including mines and people’s basements.

“The risk [of] damaging delicate ecosystems that have evolved for hundreds of thousands of years is far less when you’re working a site that is still actively being mined,” Hoyt says. “We’re targeting some of these more heavily disturbed and maybe less delicate ecosystems.”

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Nothing screams spooky season quite like vampire bats. The leathery wings, snarling snouts, and of course, the blood-exclusive diet, all make these one-of-a-kind mammals into real-life monsters. However, in reality these seemingly terrifying creatures are actually quite friendly—at least with one another.

A study published on Halloween in Cell Biology found that vampire bats develop and maintain social bonds resembling friendships. Biologists knew these creatures were uniquely hospitable with one another due to their rare grooming and food-sharing habits. But until now, scientists had been unable to prove they formed long-standing relationships.

Researchers Gerald Carter, an associate professor at Ohio State University, and Simon Ripperger, a postdoctoral fellow with the Smithsonian Institute, hypothesized that bonds between bats developed during captivity would continue after they were released back into the environment. For the study, the researchers had two groups of bats commingle: one cohort was captive-born and another (200 of them) was from a wild colony.

To induce relations, the scientists fasted each bat one at a time. When a bat is starved of blood for a night their peers will regurgitate last night’s dinner as a “food donation” and comfortingly groom one another. According to Carter, females are the only ones to perform this behavior. (It seems to Carter that males are too concerned with fighting one another over established territories to form friendships.)

After spending 22 months in captivity, the bats were released back to their home—a hollow tree located on a Panamanian cow pasture that reeks of bat poop. To track the bats’ social interactions, the team glued tiny sensors developed by Ripperger and his colleagues who are electrical engineers and computer scientists to the back of the bats. Lighter than a penny and around the size of a fingertip, these automated sensors are unique in their ability to track social networks of small animal groups by measuring their proximity to one another. They, unlike other proximity technology, are able to capture evolving relationship webs even in hard-to-access sites like small caves, or in this case, stinky hollow trees.

What these sensors found was that bats with a bond in captivity clustered close together despite being able to go anywhere or associate with any of their other 200 roommates.

“Our findings demonstrate this method of high-resolution tracking can reveal relationships that have ecological consequences,” says Carter. Prior scientific evaluations of “friendship” in animals comes almost exclusively from research in primates. “We can now see some animal relationships are independent of setting.”

However, not all friendships withstood the test of time. After only six days, the captive-born bats took flight after failing to assimilate with the colony. Even the ones born to wild bats were ousted. It is important to note that the study’s observations only chronicle eight days due to the sensor measuring the bats proximity to one another falling from one of the test subject’s backs. Therefore, researchers cannot be sure how long these “friendships” last past a week.

“It is a neat illustration that shows how the social structures of animals depend both on internal preferences they have for each other, but also the external environment because not all bonds lasted,” says Carter who has studied vampire bats for a decade. “Even in a completely different setting, these bats were still attracted to each other.”

If you are following along, sustaining 20 or so blood-sucking mini monsters required a lot of blood. To sustain these vampire-like creatures, twice a month Carter and Ripperger drove to a local slaughterhouse to fill a five-gallon bucket full of burgundy beef blood. They then drove the car hastily back to the lab (blood spoils quickly) where they froze the gory goo in bottles. Only once did they spill the entirety of the bucket’s contents in Carter’s backseat. When feeding time came around, the frozen blood was dispensed through plastic tubes that formed small reservoirs of the liquid.

“The reservoirs are usually used for giving water to birds, but we just use blood,” says Carter. Him and Ripperger laugh. “We once had an assistant faint when she saw this.”

No matter how vampire bats feast on blood, one thing seems true—those who share their morbid meal are on the fast track to friendship.

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Since it was first observed in 2006, white-nose syndrome—a fungal disease spread by the aptly named Pseudogymnoascus destructans—has ravaged bats across the United States and Canada, threatening to wipe out several species. Biologists have found infected bats in 33 states and seven Canadian provinces, but potential treatments are still in their early stages.

A bacterium could prove to be a hero for these animals. On Monday, scientists reported that bats sprayed with the probiotic microbe Pseudomonas fluorescens before hibernating are more likely to survive the winter and beat the infection. “There’s a number of treatments [for white-nose syndrome] that are being worked on currently,” says Joseph Hoyt, research scientist at Virginia Tech and lead author of the study, which was published in the journal Scientific Reports. “This is the first one that is shown to be effective in a field study.”

The fungus takes advantage of the flying mammals during their winter hibernation, when they roost in caves and wait out the cold by living on stored fat. The pathogen thrives in the cool and moist conditions of caves. While the bats try to snooze, it grows into a visible, fuzzy mold on their faces. The infection irritates the bats, causing them to wake up and burn through stored fat. The hungry, sick animals will often leave their shelter in the dead of winter, after which they starve or succumb to the cold.

Scientists are trying to save these bats by finding ways to slow fungal growth, allowing the creatures to make it through the winter. In previous work, Hoyt found that bats that were seemingly resistant to the fungus naturally carried the Psuedomonas microbe. So, he wanted to see if inoculating at-risk individuals with this organism could boost their survival.

In fall 2015, Hoyt and his team started a field test of the probiotic, using 89 little brown bats that roost in an abandoned mining tunnel in Wisconsin. They weighed the bats to assess how much fat they’d stored and outfitted them with tracking chips. The scientists sprayed some of the bats with a probiotic solution and left others dry—a control. They placed half of the bats, including probiotic and control, in cages, and left others to fly about freely.

Among the probiotic-treated free-flying bats, 46.2 percent left the cave after March 8, roughly the date when it was warm enough for them to survive and there were plenty of insects to feed on. That survival rate is five times greater than the control bats, 8.5 percent of which died in the cave.

The caged bats didn’t fare so well. There was no difference in survival between treated and control bats. Only a single bat (uninoculated) survived the winter. Hoyt thinks this is because the fungus-laiden bats frequently disrupted healthier neighbors in the cages. So even bats with less fungus struggled to survive because they were constantly getting woken up and burning through their fat reserves . “That means we didn’t actually test the efficacy of our treatment,” says Hoyt. “We included [the cage experiment] because … our window to work with bats is so limited. We need to be learning as much as possible from each other as we can.”

The results of the study are encouraging, says Jonathan Reichard, national white-nose syndrome assistant coordinator for the U.S. Fish and Wildlife Service. “Everyone I talk to is eager to have this kind of information,” he says. “This improved survival [finding] is a really positive step.”

Reichard still has his concerns. Scientists will need to figure out how to scale up the probiotic treatment to protect more bats, he says. In the experiment, researchers sprayed each bat individually with a spray bottle. And using live organisms is inherently risky. In the study, the team had previously swabbed the bats of the mining tunnel and found that P. flourescens was already present on some; that way, they weren’t introducing a totally new bug. “The whole problem we’re dealing with is because a fungus is moving around the country,” says Reichard. “We need to be especially cautious to make sure those [probiotic] microbes are not going to cause more harm than good.” But the scientific community seems more optimistic than ever now that some bats can be saved from this puffy white scourge.

Scientists in other parts of the country are looking for beneficial microbes already present on local colonies of bats. By isolating local strains of the helpful bacteria, researchers can avoid introducing new organisms, which can sometimes have unintended negative consequences. The goal would be location- and species- tailored probiotics for sick bats, says Reichard.

Still, more than half of the treated, free-flying bats in Hoyt’s experiment died, meaning the Pseudomonas fluorescens probiotic is far from a miracle cure. Hoyt notes it may be possible to modify the dose or combine it with other treatments. Scientists are testing other options, including a vaccine, which a recent study found effective in captive bats. It may also be possible to use an antifungal agent to clean the caves prior to winter, enhancing the bats’ odds. “I think it will take a lot more than just this [probiotic], there’s no silver bullet,” says Hoyt. Still, he adds, “this definitely is one more tool that we have to try to reduce disease impacts.”

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While hunting for dinner, the big brown bat must hone in on flitting insects and keep track of its surroundings to avoid crashing into them. Now, scientists have taken a peek at what’s going on in these bats’ brains while they swoop and dive. They identified a brain region that helps the animals map where objects are in relation to their own bodies, and saw that individual brain cells changed their behavior while the bats focused their attention on a particular object. The findings, published April 10 in the journal eLife, could help us understand certain aspects of attention issues in people as well as how bats and animals navigate while on the move.

Bats are a good starting point to learn about how the brain manages this trick, because their echolocation cries can reveal exactly what they are paying attention to while sizing up their surroundings. “Every time it vocalizes, it’s as if it’s shining a flashlight beam upon the world,” says coauthor Melville Wohlgemuth, a behavioral neuroscientist at Johns Hopkins University in Baltimore. A bat can adjust this beam of sonar when it wants to get a better “look” at a particular item. By squeaking more quickly, the bat captures more detailed information.

“We’ve seen for decades that they change their vocalizations to get better resolution in the environment, but it’s never been shown on a neural level what is actually happening,” Wohlgemuth says.

To find out, he and his colleagues implanted a wireless device to record electrical activity in the midbrains of big brown bats, then let them fly around a room with plastic canisters hanging from the ceiling. As the bats fluttered around these obstacles, the scientists videotaped them to track the animals’ flight paths and where they aimed their heads. The team also recorded the bats’ echolocation calls.

By putting all this information together, the researchers could figure out which brain cells became active when the bats noticed obstacles. They saw that a region called the superior colliculus encodes where these objects are positioned in three-dimensional space as the bat moves about.

This brain region is found in all vertebrates. Until now, scientists have been limited by bulky brain recording equipment and mostly spied on this brain area in stationary animals performing unnatural, two-dimensional tasks like watching a dot move on a computer screen. “We really wanted to look at his from the perspective of how the brain operates in the real world,” Wohlgemuth says. “To have an animal fly unencumbered and record wirelessly from the brain is really only a recent capability.”

It turns out that different neurons in this brain area are tuned to different patches of space around the animal. So if a bat is flying about, certain neurons might fire when it approaches a tree branch that is off to its left, twenty feet distant, and hanging at the same height as the bat. Others might become more active as the bat’s sonar pings bounce off a deer wandering below, or a lamppost directly ahead.

And when a bat inspects a particular object, individual neurons start to behave differently. As the bat squeaks more rapidly, the region of space that prompts each neuron to fire shrinks. “When the bat pays attention to an object, the representation of that object sharpens in the brain,” Wohlgemuth says. In other words, the bats could build a more precise mental picture of the location of whatever they were squeaking at. In humans, something similar might happen when we focus our gaze on an item to see it better.

Scientists believe that the superior colliculus also helps animals react to the sensory input it gathers. It might prompt a bat to shift its flight path to avoid hitting a tree, or start rapid-fire squeaking to capture more information. In future, Wohlgemuth and his colleagues would like to investigate how motor neurons in the superior colliculus behave as the bats fly about.

In people with attention issues, researchers suspect the superior colliculus does not function normally, perhaps in ways that make them more easily distracted by sensory input. Understanding how activity in this brain area shifts when an animal is trying to pay attention could perhaps help identify how these processes might be faulty in somebody with ADHD, Wohlgemuth says.

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First, let’s dispense with the myths. Bats aren’t blind. They won’t fly into your hair. The vast majority do not carry rabies. Bats are not flying mice. Only one bat — the vampire bat — drinks blood, and it’s not likely to be yours. Finally, if someone says you have bats in your belfry, it’s an insult to both you   and to bats.

Bats deserve respect. We need them. They feast on insects that destroy crops and leave behind guano, an excellent fertilizer. Bats also pollinate plants like cocoa, banana, mango and agave. The vampire bat produces a powerful anti-coagulant in its saliva that’s used in a human drug to prevent strokes. Oh, and  they just so happen to be the only mammals that can fly.

“Every time you eat corn-on-the-cob, you can thank bats for their role in managing populations of the corn earworm moth,” said Phillip Stepanian, a meteorologist with Rothamsted Research who studies the world’s largest colony of bats at Bracken Cave in southern Texas. “Even if we can’t convince you that bats are adorable, it’s hard to deny their important role in agriculture. Bats really are unsung heroes in our food production systems, and it’s our responsibility to understand the forces that threaten them.”

Today, climate change is one of those forces. It’s prompting bats — like many animal species in recent years — to change their behavior to adapt to a warming planet. Those small changes are sending ripples through ecosystems.

“Ecosystems are a complex web of connections, and it is difficult to change one component of the system without affecting the larger system,” Stepanian said. “When we observe a change in bat behavior, we have to wonder if it is an effect of some other change and whether it will result in additional changes elsewhere in the ecosystem.”

Data from a weather radar indicate that bats are migrating to Bracken Cave from Mexico roughly two weeks earlier than they did in 1995, arriving mid-March rather than late March. Some of them are also hanging around through winter instead of returning south, according to a new study in Global Change Biology authored by Stepanian and Charlotte Wainwright, also a Rothamsted meteorologist.

“When the radar detects bats flying out of the cave, it is because the bats are going out hunting for flying insects,” Stepanian explained. “During the winter, we wouldn’t expect to find many insects flying around, which is why most bats migrate back south where temperatures are warm and insects are abundant. When we see bats arriving earlier in the spring, or remaining over the winter, it suggests they have enough food to support them.”

It’s likely that more insects are surviving the winter —supporting more year-round bat residents in Texas— and that warmer overall temperatures are spurring those that do leave for Mexico to return to Texas earlier, according to Stepanian.

This insight into bat behavior was a surprising finding, since the researchers’ initial goal was to see whether they could monitor bat populations remotely without disturbing the colony. Stepanian said the subject is worthy of further study.

“When we observe a change in bat behavior, we have to wonder if it is an effect of some other change, and whether it will result in additional changes elsewhere,” he said. “For example, will changes in the timing of bat migration have an effect on their ability to regulate pest populations? Will farmers have to compensate by using more insecticides — and what further effects would that have on the ecosystem? At this point, we really don’t know.”

Bracken Cave is the summer home of more than 15 million Mexican free-tailed bats (Tadarida brasiliensis), and is the world’s largest bat colony, according to Bat Conservation International (BCI), which manages the cave near San Antonio. “The bats at Bracken Cave are an incredible natural phenomenon, and it is fascinating how we can monitor changes in their behavior over time using weather radar,” said Winifred Frick, BCI’s chief scientist.

In recent years, the cave has come under increasing stress from urbanization. BCI bought the land where the cave is located in 1992, and — with donations from its supporters — has continued to buy surrounding land to protect the bats and other native species from encroaching subdivisions.

“The nightly emergence of bats from Bracken Cave is a wondrous sight,” Frick said. “Millions of bats fly out of the cave and take to the night skies. Watching millions of bats fly out en masse is a spectacular event that is hard to describe, but one that you never forget once you’ve witnessed it.”

Stepanian agreed. “People don’t often encounter bats, certainly not as often as birds or butterflies, so they often get lumped in with other mysterious things that go bump in the night,” he said. “But public perception is changing. We often don’t get a chance to experience the epic scale of natural phenomena in our everyday life, and it’s easy to forget how spectacular our world is.

“These mega bat populations in the south-central United States give people access to a natural wonder,” he added. “After witnessing millions of bats taking flight into the sunset — just as they’ve done for thousands of years — it’s easy to appreciate how important they are.”

Marlene Cimons writes for Nexus Media, a syndicated newswire covering climate, energy, policy, art and culture.

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There are at least three things that those of us with a passing knowledge of bats know to be true. Bats are nocturnal. They have weak eyesight and thus navigate their dark world using echolocation. And they live in caves. But the truth is more complex. Some bats do fly during the day. Some bats, like fruit bats, have perfectly fine vision. And not all bats live in caves.

Here in the United States, many bats on the East coast do live in typical underground caverns, but there are plenty of places where bats have alternative housing options. “As you get further west they don’t have many traditional caves and mines. Like in Nebraska they don’t have very many,” says Catherine Hibbard, a public affairs specialist with the U.S. Fish and Wildlife Service. But while those states lack caves, they do have bats.

“They have some mines in Washington State,” adds Hibbard, “but the bats, especially little brown bats and Yuma bats don’t seem to be using them. We really don’t know where they might be hibernating.”

Which raises the question: where are these bats hiding out?

The question has taken on new urgency since the emergence of white-nose syndrome, a fungal infection that has wiped out more than 6 million bats in the United States a result of the introduction of the fungus, Pseudogymnoascus destructans, in the early 2000s.

The bats that Hibbard mentioned are species that are particularly susceptible to the disease and whose populations have been decimated by its introduction. A decade ago the little brown bat was the most common bat in the country, numbering in the millions. But 2015 research by the United States Geological Services says that in the Eastern United States, where the disease has run rampant, bat populations could decrease to less than 100,000 animals. Knowing more about where bats are and how they use their environment might be key to tracking the disease’s spread and sustaining their populations.

“Last year was the first year that they confirmed white-nose syndrome in Rhode Island. It wasn’t that we didn’t think white-nose syndrome was there,” says Hibbard. “But Rhode Island doesn’t have caves or mines, and it took a while for them to track down where these bats might be.” It turns out that those bats were hanging out in culverts.

For their long winter naps, bats need a warm, moist, dark, and quiet place to hibernate. Often, that’s a cave, but other places, like culverts, offer a suitably bat-cozy environment to snuggle in for a few months.

Researchers are now working to find out these other bat hangouts. The hope is that by finding where bats are located, the biologists may find places that are refuge from Pseudogymnoascus destructans, the fungus that causes white-nose syndrome. At the same time, according to Hibbard, we don’t know that much about bats, and this could provide crucial information into bat behavior.

“We’ve been doing acoustic monitoring in the fall around the areas where we’ve been detecting white nose syndrome, to try and pinpoint these habitats where bats might have higher activities, so around talus slopes and cliffs which might suggest that they are using these features in the winter either to roost or foraging areas,” says Abigail Tobin, white-nose syndrome coordinator for the Washington Department of Fish and Wildlife.

If you look at the map of where white-nose syndrome has spread, Washington State stands out as anomaly. Before 2016 the farthest west the disease had spread was in Oklahoma. But that year, for reasons nobody yet understand, it suddenly jumped to Washington. Like on the east coast of the United States, it wasn’t until the emergence of the disease that researchers began to heavily study their bat populations. What we do know is that there are noticeable differences in bat behaviors. The biggest is the fact that while in the eastern part of the US bats can hibernate in groups reaching thousands, in the West the bats that are susceptible to white-nose, such as the Myotis bat, tend to roost in populations of one or two and generally not in caves.

“They’re dispersed across the landscape and are using a variety of habitat to survive,” says Tobin.

Biologists like Tobin are using acoustic monitoring to get a sense of where the bats are. But to understand specific use—is this location used for hibernating, or just roosting—more detailed research is required. Some of this research, like tagging bats, hasn’t yet been done—in part because it’s really hard, and often involves heading into landscapes that are far more friendly to animals that fly than animals that walk. One of the few places where some of that work has been done is in Maine.

“We suspected as biologists that bats stayed in other environments besides caves,” says Bruce Connery a biologist in Maine’s Acadia National Park. “But because that’s really hard to find we had never been able to check that out.”

Because mid-coastal Maine, where Acadia is located, doesn’t have very many caves, the thought for a long time was that the bats did a kind of long distance commute. In spring, went the reasoning, they would travel 200, 300, 400 miles to Maine from caves in New York, Vermont or Western Massachusetts and then conduct a return trip in the fall as temperatures dipped. But around 2010, as bat research ramped up because of white-nose syndrome, Connery and his team of researchers realized that they were still finding bats late into October and that the bats would show up really early in the spring. This would have meant that the bats were traveling those large distances on nights when the temperatures in interior New England were way below zero—and the insects’ the bats depend upon for food would have been in short supply. This didn’t make sense, so Connery and his colleagues started looking closer to home for places the bats could be hibernating.

Acoustic monitoring—that is setting up audio recorders designed to listen out for bat calls—helped lead them to a geological formation known as talus slopes.

“New England was covered with glaciers 10,000 or so years ago,” says Connery. “As they left they put different pressures on the land and those rocks crumbled off the side and they fell into these heaps off the side at the toe or at the base of the slopes.”

Those slopes aren’t solid rock, however. While the faces contain openings that are relatively small by human standards, they can lead to gaps large enough to fit everything from a single bat to dozens of bats. By tracking the bats to these slopes, they were able to set up nets to track the bats and affix transmitters on them to see where the bats were traveling. Technological advances helped as well. Before 2010, the batteries needed to power the trackers were too heavy to affix onto a bat. But by 2010 they had shrunk enough in size to make this kind of tracking feasible.

These days, Connery and his colleague strongly believe that talus slopes don’t just serve as roost sites for bats in the summer, but because they’re often warm and have an internal moisture – not unlike caves – bats use them through the winter. The tracking data showed that some bats do stick around through the Maine winters.

“Apart from the rock faces places there are number of states that are looking in other types of locations,” says Hibbard. “In South Carolina they’re looking in rock shelters, and in Delaware they’re looking at old military bunkers, and there are a number of states where they’re looking in culverts and cisterns and wells”

Researchers are also leveraging citizen science projects. Many states ask people who know where there’s a bat colony to report that information to their state’s bat biologist. If they know where the bats are in the summer, they could begin seeking out where the bats are hibernating come winter.

“Bats play an important role in our ecological services,” says Tobin. “They are great for pest control they eat tons of mosquitoes and moths that damage agriculture, there are several seeds that are pollinators that help to disperse seeds. Without them you’ll lose that key role in our environment. We’ll probably start seeing cascading effects from that if we lose a key part of your bat population.”

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At a sprawling 1700 acres Washington, D.C.’s Rock Creek Park is a classic big city park. Surrounded by apartments, offices, and infrastructure, it’s a mixture of trees, trails, and pockets of nature that feel like wilderness. It is also home to bats. Many cities—from the District of Columbia to New York City to Los Angeles—are home to flying mammals from the genus Chiroptera, better known as bats. Though concrete canyons might seem vastly different from a cozy cave, bats can thrive in cities.

“For the most part we do still have good urban habitat,” says Lindsay Rohrbaugh Wildlife Biologist with the D.C. Department of Energy and Environment, pointing to parks like Rock Creek or DuPont National Arboretum in D.C. as places where bats have access to a protected natural setting. “And a lot of the common bats, like big brown bats, have adapted to what they have—people are finding them in their homes roosting,” Rohrbaugh says.

Rohrbaugh has studied the bat presence in D.C. for several years. The department’s interest in the animals began when white-nose syndrome, a fungal infection introduced to the United States from Europe in 2006, began to decimate bat populations across the country. Since then, more than six million bats have died across the United States and Canada. And while D.C. has also seen a decline in its bat populations, the city still has isolated pockets of bat species like the Northern Long-eared bat that have been all but extirpated from nearby states.

“There are places in Virginia and Maryland that don’t see them anymore,” says Rohrbaugh. “So, why are they here in the city? Maybe there’s some place that they’re going where they’re not being impacted by the white nose.”

Rohrbaugh is trying to find out, using techniques like mist netting and acoustic surveys. Mist nets help trap bats, allowing researchers to band them, and perform noninvasive tests. Acoustic surveys let biologists count the number and types of bats that fly by a location by recording their echolocation calls; different species of bats have different calls. Computer software can analyze the recordings for frequency and bat type.

That said, her research is limited by the fact that before white-nose syndrome emerged nobody was really studying city’s bats, so we don’t really know how many bats there are compared to the past. Rohrbaugh’s only clue of how many bats were in D.C. was one study that only covered part of the city. And it’s a problem that’s not just limited to D.C. or other urban centers—many areas didn’t do comprehensive surveys of their bat populations before white-nose syndrome struck in 2006.

“Before, people probably didn’t see the importance of urban bats because bats were plentiful then and we weren’t concerned about them,” says Rohrbaugh. “A lot of funding goes towards things we’re concerned about studying. If the species isn’t declining, nobody is concerned about it.”

Of course, as white-nose syndrome illustrates, theres’s a problem with that funding cycle. Without basic research and a good understanding of what a normal ecosystem looks like it makes it that much harder to assess the situation when something goes wrong.

Still, as bats numbers decline, projects like the Urban Bat Project are educating people about the importance of bats, even in urban settings. Bats can help control insect populations and pollinate plants. Now, a growing number of people are starting to build bat houses, which give bats a place to roost during the day and raise their young. Cities like D.C. are beginning to arrange bat walks where people go out around dusk to see the nocturnal animals fly out from where they’re roosting during the day. They’re also beginning to pant bat gardens with the sorts of native plants that attract pollinators like bats who feast on insects. If you want to join in on the game, the Organization for Bat Conservation has tips on building your own bat garden.

In the meantime, researchers like Rohrbaugh will keep an eye on these flying city-dwellers.

“This is a terrible disease that has impacted bats suddenly,” cautions Rohrbaugh. “We have a long way to go before we have all of the answers and there’s a lot more work to be done. Even in cities.”

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Thousands of years ago, the United States was home to vampires. Fossils of multiple vampire bat species have been found in California, Texas, Florida, Arizona, and other states, dating from 5,000 to 30,000 years ago. Since then, winters in the southern United States have become cooler. But vampire bats still roam Mexico, Central America, and South America. And now, they are on the move. The common vampire bat (Desmodus rotundus) is pushing into new territory in both North and South America, and bringing new variants of rabies along for the ride.

New research indicates that the bats’ population is on the rise at the northern edge of their range, and they may even return to the United States as climate change renders parts of Texas and Florida hospitable once more. “They’re very social and gregarious animals that have coexisted with humans for a really long time,” says coauthor Antoinette Piaggio, a molecular ecologist at the U.S. Department of Agriculture. “We’re not trying to portray these animals as something we should all be scared of.”

It could be that an infusion of blood-sucking bats will not even lead to a noticeable rise in rabies in the United States. Still, scientists must prepare for a possible vampire bat invasion. They are trying to predict where the bats will arrive, what the consequences will be, and how to prevent vampire bat-borne rabies from spreading into new places.

Returning stateside

As the only mammals to feed solely on blood, vampire bats are well suited for their special meals. They can detect where blood is flowing closest to the surface of an animal’s skin, recognize an individual animal’s breathing so they can prey upon it night after night, and escape if the animal stirs by springing from all fours right into flight.

Vampire bats are not, however, well adapted to the cold. The 2-ounce bats, which are found from southern Argentina to northern Mexico, are kept in check by chilly winters. Vampire bats are thought to be limited to areas where the average coldest temperatures don’t dip below 50 degrees Fahrenheit. Yet in recent years, people have started reporting vampire bats at higher elevations and farther north than before, Piaggio says.

Within the past 5 years, vampire bats have been documented within about 30 miles of Texas. The bats are multiplying in areas where they were once uncommon, Piaggio and her colleagues suspect. They’ve taken wing tissue samples from hundreds of bats, and found evidence in the animals’ DNA that the population had grown rapidly and recently in the northeastern edge of their range in Mexico.

But speed is relative. The bats could have started increasing in the past decade—or hundreds of years or more in the past. “It could have been as far back as when Europeans first arrived,” Piaggio says. The livestock that the colonists brought with them in the 15th and 16th centuries could have provided the bats with more prey, allowing them to increase their numbers. In future, examining more of the bats’ genomes could help the team pinpoint the their rise more precisely, says Piaggio, who published the findings in the journal Ecology and Evolution in June.

If the bats are marching north, they might find appealing real estate in the southernmost United States. Piaggio and her colleagues are investigating where vampire bats could cross the border using current and worst-case future climate conditions through about 2070.

“A very small part of the southern tip of Texas could currently be representing suitable habitat for vampire bats, and so it’s possible that vampire bats could currently be spreading north,” says team member Mark Hayes, senior bat ecologist at Normandeau Associates, an environmental consulting firm headquartered in Bedford, New Hampshire.

In the next few decades, other parts of southernmost Texas and the southern half of Florida could become warm enough to host vampire bats. Hurricanes could blow the bats from Mexico’s Yucatán Peninsula into Cuba and then Florida, Piaggio says.

While vampire bats could perhaps settle in a sliver of southern Texas, there’s no way to know if or how soon they might arrive. It’s possible that incursions into the southern parts of Texas would be a seasonal affair. “They’re very social animals, and even if males disperse they might not stay because they couldn’t set up a harem of females and reproduce,” Piaggio says.

The vampire bats would likely only colonize a pretty small area. What’s more, rabies doesn’t affect a large portion of the population, although the wounds the bats leave behind can still harm an animal’s health if they become infected. “It might even be that we end up with vampire bats and no or very little rabies transmission,” Piaggio says. “Maybe they would feed on feral swine and deer and we wouldn’t ever really pick it up.”

If the climate in southern Texas and Florida shifts and winters become warmer, the bats would have a fair shot of surviving up north, says Daniel Streicker, a disease ecologist at the University of Glasgow in Scotland. “I think it’s going to be a pretty slow invasion,” he says. But, “I don’t see why they couldn’t move up into the U.S.”

Ready to mingle

Understanding where vampire bats from different areas meet up could help scientists predict how rabies will spread. For now, Streicker says, rabies is not found in vampire bats along the western coast of South America. But that may change within a few years.

To estimate how quickly the virus could travel, Streicker and his colleagues pored over records of past rabies outbreaks, noting which version of the virus was responsible for each. They also captured vampire bats from around the country, and examined variants of the virus that had shown up in different areas. The team found genetic evidence that male vampire bats are responsible for bringing rabies to new territory, likely when they leave their families to seek out a harem of females to breed with.

The team also found genetic similarities in bats on the eastern and western slopes of the Andes. Vampire bats, it seems, are not blocked by the mountains, and could bring rabies with them over this route. Already, farmers and vets are reporting vampire bat bites on livestock at higher and higher elevations in the Andes. The researchers have calculated that vampire bat-borne rabies could reach the Pacific coast of South America around 2020.

Streicker has also documented “waves” of genetically related versions of rabies moving through livestock in Peruvian valleys. This indicates that variants of the virus carried by vampire bats hadn’t existed in these regions previously, and are only just arriving. Local farmers told Streicker that they were used to dealing with vampire bats, but the rabies was only a recent problem. He then examined strains of the virus from around the country and saw a similar pattern, implying that rabies is on the move in many places.

It’s not clear why this is happening now. It could be that vampire bats are moving into new areas, and the virus takes a few years to catch up. Climate change could be making mountains less impassible, allowing bats from previously isolated colonies to meet.

Humans might also be unwittingly bringing vampire bats together. As farmers bring livestock into new areas, the bats could feast over broader terrain and encounter bats from neighboring colonies. And when people build tunnels and mines, they create new housing for bats in areas that might have otherwise lacked tempting roosts.

Another possibility is that rabies has only been circulating in the vampire bat population for a couple centuries, and hasn’t had a chance to spread to every corner of the bats’ range.

Streicker is now studying the economic problems vampire bats cause by spreading rabies to livestock. Many of the communities where bat-borne rabies is now invading rely on small-scale subsidence farming. When a single cow sickens and dies, it can represent the loss of a month’s income. “It can be totally devastating,” Streicker says. “When they sell a cow, it’s going towards childhood education or towards repairing their houses.”

He’s heard that many people are giving up on raising animals altogether. “They’re either moving to cities or they’re switching to raising things like oranges or avocados, because it’s just so unsustainable to raise cattle in areas where there is rabies,” he says.

Bracing for impact

The U.S. Department of Agriculture’s National Rabies Management Program has begun to prepare for the possible arrival of vampire bats and any new strains of rabies they might bring to the United States. They are surveying cattle at cattle sales barns, feedlots, and on dairy farms for vampire bat bite wounds in Texas, Arizona, and Florida. In 2017, they examined more than 95,000 cattle, and did not find any vampire bite wounds. They are also educating farmers and wildlife biologists in the borderlands to recognize vampire bat bites.

Their goal is to minimize any risk to people, pets, and livestock without demonizing the bats. “While the mention of the word rabies strikes fear [into] people there are very straightforward ways to minimize the risk of being exposed,” Richard Chipman, the rabies management coordinator, said in an email. “Vaccinating pets and livestock and avoiding strange or sick acting wildlife remains the best first line of defense.”

These steps, however, will not halt the spread of rabies within the bat population.

“We can vaccinate humans and livestock all day long, but at the end of the day those species don’t contribute anything to the onward transmission,” Streicker says. Yet culling the bats hasn’t reliably worked to stop the spread of rabies, either, he says. In fact, this tactic can actually spread diseases even farther.

People sometimes try to kill vampire bats by lighting their caves on fire or attacking them with large sticks. This can drive the bats out to seek new homes, bringing rabies into new areas. “The bat has no reason to stay inside this cave [where] it’s being lit on fire and persecuted all the time,” Streicker says.

Another technique for killing vampire bats is to spread a poisonous paste on one bat’s back, then release it. When the bat rejoins its fellows, they will begin to groom it and lick the poison from its fur. “Some of the ones that might be incubating rabies but aren’t sick yet might realize, ‘there’s something strange going on here, all of my friends are dying,’ and so they might fly farther away to try to escape,” Streicker says.

There might be a more effective way to slow the virus’s spread: swapping the poison out for vaccines. So far, oral vaccines seem to work well in captive vampire bats, including when the bats swallow it while grooming each other. For now, though, these vaccines are still in development and need additional safety testing; it will probably be a few years before they can be tested in the field.

Vampire bats do pose a substantial risk in terms of their ability to spread rabies, and they are more abundant now than ever before, Streicker says. In Latin America, they are the main cause of rabies outbreaks in people. But on the whole, it’s rare for people to be bitten by vampire bats in agricultural areas; if there are livestock around, the bats tend to feed on them rather than people. People can get rabies from infected livestock, but in practice this doesn’t happen much, Streicker says.

Vampire bats have the potential to do a lot of damage; in some parts of Mexico, rabies kills up to 20 percent of unvaccinated cattle. But in the United States, their impact is likely to be more limited.

“The arrival of this unique and interesting species and eventually a novel (at least in the U.S.) rabies virus variant is not a catastrophic event or cause for significant alarm,” Chipman says. Even if it sounds a little bit spooky.

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From acoustic recorders to special ultraviolet lamps, biologists are calling on a suite of tools to better track, understand, and hopefully save America’s favorite (and, admittedly, the planet’s only) flying mammal: bats.

The need to understand these elusive creatures has increased in recent years with the emergence of a disease called white-nose syndrome. The fungal infection was introduced into the United States from Europe around 2006, and has killed more than 6 million bats over the past ten years. But as the bats have died, our awareness of how critical the creatures are to our ecosystem has grown. Bats help pollinate our plants, and reduce the number of insect pests. The fact that bat populations are on the decline is not a good thing.

While white-nose syndrome is the most obvious threat to bats, it isn’t the only one. The warming temperatures associated with climate change affect a bat’s ability to echolocate—the way bats navigate in the dark. Humans are also encroaching on bat habitats in more direct ways. We are cutting down the forests where some bats live and others like to hunt, and otherwise destroying their homes with our development.

And while wind turbines are an environmental boon in that they help produce electricity with a lower carbon footprint, depending on their placement they can also harm bats. Bats sometimes confuse them with trees and other roosting locations. Instead of heading away from wind turbines, they head towards them. In the process, they risk a deadly encounter with the structure’s blades.

Other man-made materials can also pose a risk. Super slick surfaces—like the coatings on glass buildings—mess with the way some bats use echolocation. As we erect more of those types of buildings, more and more bats slam into them—to their death.

Bats must meanwhile contend with another issue: less food. Studies suggest that worldwide insect populations are declining, even within protected areas. As all bats in the United States are insect eaters, the drop-off in these smaller fliers doesn’t bode well for our winged mammals.

Even worse, increasing data suggests that insects may be harmful to bats in another way. When bats come into contact with the pesticides we spray in an effort to get rid of harmful bugs, either by eating contaminated insects or hanging out on plants that people have spritzed, they get sick.

If this seems bleak, there is one small bright spot: the cool equipment and techniques that biologists and other researchers have developed to study bats. If you’ve ever wondered how researchers catch a bat or track its movements, we’ve created a photo gallery showing some of the equipment that researchers use to do their job. Here’s a look at some of the gadgets they use to get the job done.

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I’m somewhere around 40 stories down when it hits me just how much we’ve lost. I am inching through tight cavern rocks on my stomach, hitting my (thankfully helmeted) head each time I give into instinct and attempt to look up. The cave ceiling is very close to the cave floor. The spelunkers winnowing their bodies through these sinuous crevices are likely the only vertebrates in this cave system. But just a decade ago, it was home to thousands of bats.

They’re all gone now, apart from five long-eared bats that flit in occasionally. The other bats—mostly little brown bats—were wiped out by a fungus, Pseudogymnoascus destructans. We can’t see the fungus that causes white-nose syndrome lining the rocky walls, but we have it on good authority that wading through the Pennsylvanian cave’s muck has left us covered in the stuff.

I take a deep breath and wonder if Pseudogymnoascus destructans is inside me, innocuously mixing with the bacteria, viruses, bacteriophages and other fungi that form my lung’s microbiome. Unlike the bats, I can take it. The fungus doesn’t seem to affect humans. It’s around then that I realize this cavernous world has become liminal, a place of transition between the old world—where you could see bats darken the sky at sunset as they fled—and this new world, where some species of bats have been wiped out entirely.

As far as anyone can figure, it was cavers who brought Pseudogymnoascus destructans to the United States. They inadvertently introduced the pathogen to a cave in Eastern New York State sometime in the early 2000s, though the first documented case was in the winter of 2006.

White-nose syndrome is now in 31 states and five Canadian provinces, moving south and east and petering out towards the Midwest. This year, though, it popped up in the Texas panhandle, and for reasons nobody understands managed to leapfrog into Washington. It could be that bats living between the outbreaks aren’t getting sick, or it could be that nobody is finding them. Only time will tell.

Pseudogymnoascus destructans kills insidiously. Of the 47 bat species that call the United States home, more than half hibernate to survive the winter, when the insects that they depend on for food become scarce. Hibernation allows the bats to enter a deep slumber and live off of their fat stores. Many, including the little brown bat, huddle together in the warm areas of caves. But this pattern of behavior only hastens white-nose syndrome’s spread. The habitual huddling for warmth allows the pathogen to pass from bat to bat, and provides the perfect temperature for the fungus to grow. As Pseudogymnoascus destructans spreads across a bat’s body, it wakes up, either to clean the fungus off or because it’s having trouble staying warm. Every time a bat wakes during winter hibernation, however, its body stores dwindle, leading to dehydration, starvation, and usually death.

Nine American bat species are confirmed to have white-nose syndrome. For reasons that aren’t clear, some bats don’t get sick from the fungus. The bats that do get sick include the Big Brown bat, the Eastern Small-footed bat, the endangered Gray bat, the endangered Indiana bat, the threatened Northern Long-eared bat, the Yuma bat, the Southeastern bat, and the Tri-colored bat. But the decimation of the little brown bat seems especially heart wrenching.

There’s the fact that little brown bats are adorable. As their name suggests, they are little, with a maximum body height of around four inches and a peak weight of roughly half an ounce. They fit in the palm of your hand. And little brown bats are ubiquitous—or at least they used to be. Before white-nose syndrome, they were the most common bat in North America. Their deaths visibly loosen the bonds that keep our ecosystem together.

While bats in other parts of the world dabble with fruit and blood, bats in the United States are insectivorous—they eat bugs. There isn’t much data to back up a frequently stated claim that bats can eat 1,000 mosquitoes an hour, but they do seem to help keep the number of nuisance insects in check. Studies suggest that the mere presence of bats seems to cut down on the number of mosquitoes. At the same time, bats chow down on a number of agricultural pests like corn ear moths, and spotted cucumber beetles. And because bats flit from plant to plant as they collect insects, they also spread pollen, which means they pollinate our crops alongside bees and butterflies. As these bats die off, we lose the services they provide to the ecosystem; the ways they help farmers.

To humans, bats can seem like elusive creatures. Our eyes don’t see as well in the dark, making the nocturnal animal difficult to spot during the times they’re most active. The window in which we can most easily see bats is narrow—in the fading light of sunset when they depart their domiciles and in the dwindling darkness around sunrise as they return. So for many, the fact that white-nose syndrome has killed more than 6 million bats in the Northeast and Canada alone is all too easy to ignore.

The deaths weren’t the fault of those first cavers—not exactly. Nobody knew that a fungus powerful enough to wipe out a cave’s worth of bats was at play. And it took a while for people to catch on, with the fungi meanwhile leaping from commercial cave to commercial cave, carried by unwitting visitors. Even protected caves weren’t safe: once the disease started spreading, the bats brought the fungus in on their fur.

“The season of 2009-2010 is when we started getting ready for this,” says Lisa Hall, the director of case studies at Laurel Caverns Geological Park (where I’m currently mucking about in Hopwood, Pennsylvania). That year, when they’d had their highest bat count—some 2,500 bats of six different species—researchers at the Pennsylvania Game Commission told them that the disease had begun migrating out of New York State, and they should start to be concerned about white-nose syndrome.

“The owner David Kale, when we had our first talk and we realized this was coming, I will never forget the look he gave me,” says Hall. “Just kind of a look of hopelessness. Our bats were going to die.”

But they had to try. They stopped most of the tours into the deeper portions of the caves where the bats tended to congregate—the portions I crawled through and contemplated.

“That was a surprise to everybody, because Laurel Caverns have been open for a long, long time,” says Hall.

For the tours to the shallower parts of the caves, they placed a pad with a bleach solution for visitors to shuffle through, in effect disinfecting their shoes to emphasize the protection of the bats. They handed out pamphlets explaining how to properly sanitize caving equipment. The state Game Commission even erected nets over the mouth of the cave after the bats entered for hibernating season. Because white-nose syndrome rouses infected bats from sleep, they were afraid that sick bats from other caves might wake up and fly over.

But all of these efforts were like trying to patch a leaky raft with bubble gum; they’ll work, but only to a point. The most visited caves were the first ones to take ill.

“But the fact that Laurel Caverns didn’t get it first, the fact that it went to some natural caves south of us here and then worked its way up here, is some evidence that maybe what we did worked a little bit,” says Greg Turner, a mammalogist with the Pennsylvania Game Commission. It’s possible they successfully kept humans from tracking the pathogen in on their clothes, he says. “But it was inevitable that it was going to come via the bats.”

And white-nose syndrome did come. In 2009, they counted 2,500 bats; in 2011, they counted 25. In 2012, they counted five. If we had shimmied through the cavern in 2009, the year before white-nose made its way here, we would have seen bats throughout our expedition. But the only signs of life these days are humans, along with the fungi and bacteria that shimmer in the light of our headlamps. You can’t disinfect a cave, so Pseudogymnoascus destructans is here to stay.

The news isn’t all bleak. Increasingly, the bats that have survived infection seem to be adjusting their behaviors to put up a bit of a fight. Turner says that some of them appear to be picking hibernation locations that are in the cooler range of their comfort zone—the fungus doesn’t grow as well in colder temperatures.

There’s hope that the bats in places where the pathogen has taken hold might learn to adapt, but researchers are also working hard to curb its spread. It’s work that we will chronicle this week—the fourth annual Bat week—as we dive deep into the life of the world’s only flying mammal.

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When it comes to navigating at night, bats are among the champions of the animal kingdom. But it turns out that these fuzzy fliers do have one weakness: super-smooth vertical surfaces.

Bats find their way in the dark using echolocation—sending out sound waves and listening for their echo. Sound waves reflecting off an object back towards the bat can indicate the position of an obstacle to be avoided, letting the animal change its course.

In a study published today in Science, biologists Stefan Greif and Sandor Zsebok found that smooth vertical manufactured surfaces mess with this otherwise astounding ability.

Greif says these surfaces act like an acoustic mirror. The surface is so smooth that the sound waves ricochet off at a steep angle, only bouncing back to the bats when the creatures are positioned directly in front of the surface.

Unless a bat is perfectly lined up as it flies toward a smooth surface, it will be blissfully unaware of the giant thing looming, lost in an acoustic blind spot.

The consequences of the diverted signal can be disastrous—or at the very least, pretty embarrassing—for the bats.

Don’t worry: No bats were harmed in the making of this study. “In our experiments we didn’t see any injuries,” Greif says. “We had them in a small flight room, in a narrow tunnel where they’re flying relatively slowly compared to the speeds at which they might fly outside.”

Some slammed into the surface without changing their flight path at all. Some tried to pull back, but only did so too late. And a select few did manage to avoid the plate entirely. Greif found that those lucky bats were the ones that sent out their sound signals while directly in front of the plate, giving them enough warning to change course mid-flight.

Greif only used a small selection of bats for the study, but 19 out of 21 subjects slammed into the vertical surface at least once. When the smooth metal plate was placed on the floor, the bats didn’t collide at all.

Greif and his colleagues knew from previous studies that bats have no problems with horizontal smooth surfaces. That’s because, while there is no natural situation where a bat might encounter a vertical smooth surface, they frequently see prone smooth surfaces—every time they fly over a pond or puddle. In fact, many of the bats tried to drink from the flat metal plate (needless to say, they were unsuccessful.)

Though this study shows how smooth vertical objects can pose a problem for bats, it doesn’t show whether or not we should be concerned about this biological quirk. It might be dangerous for bats living in a world where humans—and our buildings with glass windows and metal facades—are common. But there’s no way at present to know just how dangerous this might be, or if it’s something that bats can easily shake off.

“Many bats are found injured, but people don’t keep track of what situations they find them,” Greif says. Bats are sometimes found in nature with broken jaws and wings, or even dead, all situations that could be caused by running headlong into a flat, hard surface at high speeds.

People have started tracking birds that have collided with buildings, but data on bat collisions remains rare to nonexistent. There’s anecdotal data about bats, particularly speedy migratory bats found dead next to buildings, but Greif hopes that future research and surveys might lead to a more robust data set.

“One of our hopes of this study is people start paying attention to where they find these injured bats so we can get an idea of the extent of the problem.” Greif says.

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On Tuesday morning, Amanda Lollar and three volunteers gathered up canoes, headlamps, and life jackets. Then they headed out into the floodwaters of Houston—to save bats.

A colony of 250,000 bats live under Waugh Bridge, right over the rising Buffalo Bayou. Some of them have escaped rising waters to perch on surrounding buildings, according to the Houston Chronicle. Others may not have been so lucky. When the winged creatures take off, they drop slightly before they start flying. As storm surges from Hurricane Harvey rise and the bayou gets closer to the bridge, some animals trying to flee are falling into the floodwaters instead.

Others, too cold and wet to fly, simply remain in harm’s way. Several videos have surfaced showing volunteers scooping out bats from under the bridge.

“Some of the bats did manage to get out. Others were found dead,” says Melissa Meierhofer, a wildlife researcher at the Texas A&M Natural Resources Institute. “Some were being saved. They looked pretty wet.”

It might seem like a trivial concern in the wake of so much human suffering. But that attitude could come back to bite us: A dead bat is a bat that can no longer consume huge meals made of Houston’s mosquitoes—mosquitoes that may lead to a proliferation of diseases after the flood. The colony at Waugh Bridge eats an estimated two and a half tons of insects every night. In the comments of a CBS video featuring a woman rescuing bats from the bridge with a net, several people expressed interest in helping the unlucky mammals.

On Monday, Texas Parks and Wildlife mammalogist Jonah Evans was at a loss for what people could do if they saw bats floating by and wanted to assist them. Civilians who deal directly with the bedraggled creatures are at risk for rabies—and once they get the animals out of the water, what can they do with them? All available personnel are helping with the human rescue efforts.

But now onlookers concerned with wildlife wellbeing have an option. Lollar recommends they scoop the floating bats into a bucket or box with a long stick. Then they can call the Bat World Sanctuary, which is now on the scene, or contact them through Facebook. In addition to transport carriers, the team has syringes full of bat electrolytes and emergency food. All the volunteers have rabies vaccinations and are used to dealing with these animals.

The Mexican free-tailed bat is one of the most plentiful mammals on this continent, so the species as a whole will probably be fine. Bats in South Texas have not yet suffered significantly from white-nose syndrome, like their brethren in the eastern U.S. “There might be some population decline as a result of this, but they will likely bounce back pretty quickly,” says Evans.

And even though the population would probably recover eventually, the volunteer’s efforts will make a difference for individual bats. “Dogs, cats, birds. Everything needs to be rescued,” says Lollar.

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Bats in Europe are regular churchgoers. In fact, they often take up residence in the quiet upper areas of a church, whether an attic, steeple, or belfry. Those areas don’t tend to be that popular with human congregants, so for decades—and in some cases hundreds of years—bats like the brown long-eared bat Plecotus auritus would roost in churches.

In some cases, having bats in residence is a problem. Like in the English churches that are having to figure out how to deal with massive amounts of bat guano. But in Sweden, where the brown long-eared bat lives, the bats tend to be fairly unnoticeable unless you’re looking for them.

Biologist Jens Rydell was looking for bats. He had surveyed Swedish churches in the 1980s for bat populations living in their attics. Then, he repeated the study in 2016 to see if the populations had changed. It turns out, there was a noticeable decrease in bats, and the churches where the flying flock had fled all had something in common. They’d decided to let their light shine.

For the most part, the colonies that disappeared in the 30 years between surveys were located in churches that decided to install floodlights to show off their architecture at night. In one case, the lights were installed on the interior of the church, to better show off some architectural details.

“Generally bats are faring quite well in this area,” Rydell said in an e-mail. “ But the massive introduction of lights can clearly change that. A 38 percent reduction of colonies, as we found, is a lot.” He says the loss of individual bats is likely even higher as it’s easier to kill an individual than an entire colony.

Lights focused on the bats’ home leave them vulnerable to predators like tawny owls, sparrow hawks, and housecats. Without the cover of darkness the bats have a harder time avoiding predators.

It also makes churches less appealing to bats, which don’t have natural caves to live in in Sweden, and have used the churches as a warm refuge in a cold climate for nearly 1,000 years. There are other benefits too.

“Church attics are large enough and have piles of hibernating insects such as blow flies, butterflies (tortoiseshells), and also, of course, potentially harmful insects to the wood.” Rydell says. “The bats feed on these and can thus be active even weather is unfeasible outside. They can even grab a meal if the get hungry during daytime or in the middle of the winter. Other bat roosts normally don´t have such facilities!”

Rydell says he hopes his results, published today in Royal Society: Open Science might add to the conversation about bat conservation in Sweden.

“We clearly need a communication channel between the nature and culture authorities at national, regional and local levels. At least here, decisions on issues like this (light installations) are taken independently of any natural values. The cultural heritage is also our natural heritage and vice versa.” Rydell says. “I hope that people in general start to see light pollution as what it is, introduction of a new threat to our biodiversity.”

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Jostling for food and living space can make for some tense interactions with your roommates. But just imagine thousands—or millions—of individuals spending decades sharing the same dark room. They’d need constant communication to keep the peace.

That seems to be the case even for Egyptian fruit bats, which live in large colonies and are generally social creatures. Walking into a typical roost can be a noisy experience, but are the bats just making random noises or are they actually talking to each other?

In a study published in Scientific Reports on Thursday, researchers suggest that the noisy bat calls actually do contain a lot of information, including who’s ‘speaking’ and whether the bats in a particular interaction are fighting about food, a mate, or something completely different.

“The vocalizations we looked at in this study were all categorized in the past as agonistic calls, that is, aggressive vocalizations emitted during fighting. We now show that there is information in this chaos. We demonstrate that a third individual listening to a fight between two bats can tell who is shouting, what is the context of shouting (e.g., fighting over food or over position or over mating) and even to some extent who is being shouted at. We now know that the cacophony that we hear when entering a bat cave is far from just noise,” Yossi Yovel, the lead author of the study, told Popular Science in an e-mail.

By recording a group of 22 bats for 3 months straight, Yovel and colleagues were able to figure out which bats were involved in any conversation and what they were squabbling about. But that doesn’t mean that the researchers have identified a bat language, or even the bats’ individual call signs. What they did manage to do is recognize individual bat voices.

“It is similar to humans individual voice. It is not that bats state their name, but that when you examine their voice, you can recognize who is shouting (calling),” Yovel says. “In fact, in the study, we used algorithms that are typically used for human speech recognition to recognize the individual bats.”

They could also figure out specific noises that related to food, mates, or a need for some space. But this isn’t the start of some kind of inter-species communication. (Go home Arrival, you’re drunk.)

via GIPHY

“We do not find a ‘word’ that mean ‘hello’ or ‘move’ or ‘eat’ in bat communication,” Yovel says. “You could imagine this as something like this: when a bat shouts at another bat for taking its food, the vocalizations will always be higher in pitch than when they are fighting over a position in the cave.”

The next step will be to figure out how bats know to make those noises. Are they born with this manner of “speaking” or do they learn it over time? Yovel and his colleagues are also looking into vocalizations made outside of the confines of the roost. To gather that data, they are attaching tiny microphones to bats in the field, which is adorable. Maybe someday soon we’ll have an even more detailed answer to that age old question: ‘what does the bat say?’

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Rising above the sounds of crickets chirping, the distinctive whining croak of a male túngara frog can capture the attention of a big brown fringe-lipped bat almost immediately. These frog-eating bats live in forests from southern Mexico to Bolivia, and rely heavily on eavesdropping on their prey. But when the mating calls of frogs are masked by a noisy environment, the bats are forced to use alternative cues to track down their dinner.

Instead of waggling their heads and listening for the frogs’ calls, bats start relying on echolocation to hunt when man-made noise becomes too deafening. The switch allows bats to change how they gather information about their surroundings, but it also increases the time they take to attack prey, according to a study that will be published tomorrow (Sept. 16) in the journal Science. That’s bad news, says senior author Wouter Halfwerk, an animal ecologist at VU University in Amsterdam, because as cities continue to grow and anthropogenic noise increases, an entire population of bats may have to change not only how they find food, but also how much they can forage.

Normally, the bat’s hunt goes like this: first it listens to its prey, waiting to overhear the túngara frog’s mating displays, then it assesses the frog’s size, and finally when it knows enough about the frog’s palatability and precise location, the bat swoops down and swallows the frog whole.

To see how the bats would adapt their hunting strategies in the presence of man-made noise, Halfwerk and his team studied how 12 wild-caught bats located and attacked two robotic frogs. One frog only made the mating sounds, while the other also had a balloon attached that inflated noticeably when it croaked, mimicking the movement of a vocal sac. The researchers found that, when they added background noise that masked the frog’s mating sounds, bats attacking the motionless robot took twice as long as bats that located and attacked the robot with the moving vocal sac. In fact, the robot without the moving sac was so hard for them to detect that the bats chose the frog with the balloon sac 75 percent of the time. That’s because they stopped relying completely on their hearing to detect the frogs. They used more echolocation instead, which helped pinpoint where the movement was coming from.

“This shows that bats are much more flexible than we previously thought,” says Halfwerk. “They can actively switch which sensory cues they use, which is very similar to what humans do when we’re trying to talk to someone in a noisy environment–we start paying attention to their lip movements as they speak.”

But deciding which cues to use in a given environment may not be enough for bats, which are particularly vulnerable to noise, says Jinhong Luo, a bat scientist at Johns Hopkins University. “The bats are doing worse when exposed to noise despite their efforts to adapt. And the longer it takes them to detect prey, the fewer frogs they may be able to hunt.”

Human noise from city traffic and industries is only bound to increase in the future. Nearly four billion people in the world already live in cities, and the United Nations estimates that number will increase to more than six billion by 2050. By studying how animals like bats cope with these changes, Halfwerk hopes that scientists can better understand how the species will fare in the future. “We know that evolution is faster in anthropogenic environments, and if bats are behaviorally flexible they may just be able to adapt over time,” he says.

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When dinnertime rolls around, bats cock their heads and wiggle their ears. It turns out that these movements help with hunting. Big brown bats (Eptesicus fuscus), a common species in North America, coordinate their head and ear twitches with sonar vocalizations to pinpoint approaching prey, indicates a study published today in PLOS Biology.

To survive in the wild, animals must be able to extract important cues from the deluge of sensory information they encounter. Humans do this by focusing our gaze on an object or tilting our heads to gauge the source of a sound. Not much is known about how bats use movements to get a better lock on what they are hearing; for the new study, scientists were interested in how they might pair this strategy with echolocation.

The scientists trained three big brown bats to perch on a platform as mealworms tethered to a loop of fishing line were dangled in front of them. The fishing line was connected to a set of pulleys and motors. The scientists recorded the bats eagerly tracking the snack as it sailed towards them, measuring their movements and sonar pulses. Reflective markers attached to the bats’ ears and heads with spirit gum allowed the team to see each twitch in detail.

As their prey approached, bats adjusted how frequently they vocalized and how long each pulse lasted. Then, they cocked their heads and twitched their ears. “We discovered that the bat ‘waggles’ the head to alter the relative elevation of the ears, while also changing the separation between the tips of the ears as it engages in target tracking,” the researchers wrote.

The bats waggled more vigorously when the mealworms moved erratically, and flicked the tips of their ears as the snacks approached. Coupling echolocation with these movements helps the bats predict their prey’s location more accurately as it moves about. Understanding how animals benefit from this kind of coordination might have applications for building robotic sensory systems, the team concluded.

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Bats are powerful, graceful and precise fliers…most of the time.

While they use echolocation to dodge solid obstacles very well, sometimes the skies are just too crowded to avoid a few bat versions of fender benders. In the video above bat researchers from Winston-Salem State University set up high speed cameras to capture the movement of thousands of bats as they make their nightly exit from their home into the sky. They share their research in a video produced for bioGraphic a publication of the California Academy of Sciences.

The bats’ commute from home to work (gathering food) is just as crowded as any major interstate if not more, but somehow every day thousands of bats manage to fly out of the cave without a hitch. Researchers initially thought that the bats were able to avoid each other entirely, but as it turns out, some collisions are inevitable in the high-traffic area. Sounds just like rush hour.

Bats are still expert fliers, and most of the collisions don’t seem to result in injuries, but the bats aren’t the paragons of flight that we all thought they were. Knowing more about how bats fly (and what their limitations are) could have an impact on how other flying objects like drones are designed. Researchers also want to know more about bats because the furry flying mammals are incredibly important to the agricultural industry, providing pest control and pollination services.

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There’s this scene in one of the greatest movies of the 80s, “The Blues Brothers,” that makes me laugh and cringe every time I see it. Jake and Elwood are careening through Chicago, sunglasses on, at 120 MPH, fleeing every representative of Illinois’ law enforcement community. Elwood doesn’t flinch as he dodges every pylon on Lower Wacker Drive, narrowly missing bicyclists, pedestrians and delivery trucks. Surely he’s about to crash in a horrible spectacle, you can’t help but think, even though of course he doesn’t.

This is the image that came to mind when I read a new bat study coming out today. Like ridiculous Elwood, hunting bats effortlessly avoid trees, power lines, and each other, appearing insanely unhinged but in fact behaving very carefully. They do this in total darkness, too. They have sonar, but it turns out the way it works is actually pretty simple, the new study says.

Scientists have assumed bats must use some kind of complex echo interpretation to figure out where they are relative to their prey, relative to each other, and relative to any trees or other obstacles in their paths. But inferring everything from simple ultrasonic echoes is hard, to say the least, and might actually be impossible. Could bats really be sending and receiving that many signals that quickly?

Researchers from the University of Antwerp in Belgium and the University of Bristol in the UK tried to find out. The team used lasers to scan a chunk of forest, and used this information to build three-dimensional models of horseshoe bat habitat. Then they modeled bats flying through two-dimensional and three-dimensional versions of this environment. They came up with an algorithm that can model what the bats are doing — and it’s not complex computation of dozens of point sources simultaneously.

Rather, bats use a simple binaural trick: They compare the loudness of the echoes from each ear, and turn away from the side that gets a louder echo. This requires ultra-sensitive hearing capable of distinguishing minute differences in the time it takes to make an echo. But on the whole, it’s not that hard, and it is pretty intuitive. When it takes less time for a bat’s call to bounce back, that means an object is closer. When it takes a little bit longer, that object is farther away.

In repeated computer simulations, bats following this algorithm steered away from obstacles, demonstrating this simple input is enough.The key distinction here is that the bats don’t necessarily figure out where obstacles are located. They just know where to turn to avoid them — or, based on the echo signature, where to get a meal.

This simpler signal processing allows bats to respond more quickly, turning on a dime at high speeds to snatch moths and mosquitoes while avoiding each other. And that’s good news for researchers building drones and other robots based on bat behavior — programming them might not be nearly as complex as we thought. The work appears in PLOS Computational Biology.

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Bats may be both ecologically and economically valuable, but they are also notorious for transmitting diseases particularly rabies and maybe even Ebola. The bats themselves, however, don’t often get sick as they have impressive immune systems unlike those of any other mammals, according to a study published this month in Biology Letters.

Bats host more pathogens than most other mammals, yet they rarely get sick—however their immune systems have been so little-studied that scientists didn’t know why. In this study, the researchers tested the immune response of the Pallas’s mastiff bats, which live in Panama. They held a total of 34 bats in captivity and dosed them with a compound called lipopolysaccharide (LPS). By itself, LPS is harmless, but since it’s a chemical commonly found on the membranes of many disease-carrying pathogens, the researchers expected the bats’ bodies to respond as if they were infected.

The bats didn’t show any of the typical signs of infection—no fever, no increased white blood cell count—that other mammals would. The only sign that anything was wrong was that their body mass decreased slightly, which showed their immune systems were engaged.

These results are even more puzzling to researchers. They hypothesize that the bat’s drastic temperature changes over the course of the day might have something to do with it. When a bat sleeps during the day, its temperature drops to conserve energy, which might slow the pathogens’ spread; when it goes out at night to hunt, its temperature skyrockets to more than 100 degrees Fahrenheit, which could work like a daily fever to increase the activity of certain kinds of immune cells. Birds have similarly high body temperatures when they fly, but their bodies do respond to LPS with fever.

Overall the researchers concluded the study with more questions than answers about how exactly a bat’s immune system works. Future studies are needed to understand how their immune systems use the same cells for different roles than in other mammals, or if they stave off disease with different cells altogether. Understanding the mechanisms behind he functioning of their immune systems might also show researchers why it’s been weakened by White Nose Syndrome, which is ravaging bat colonies all over the world.

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It’s almost that time of year again.

The weather is cooling down, just in time for decorations of harvest and Halloween to adorn candy shelves and craft stores. Bushels of corn and bats are at just about every grocery and drug store in the country, but bats and corn don’t just make attractive fall-themed decorations. They’re actually colluding in a billion-dollar partnership that benefits farmers across the nation.

Scientists and farmers have known for a long time that bats were a valuable contributor to the agricultural landscape, eating pests that would otherwise be eating crops. But they didn’t know exactly how much bats helped. In a new study published in PNAS, researchers were able to finally quantify the collaboration, and found that annually bats prevent nearly a billion dollars in pest damage around the world.

To get to this conclusion, researchers (funded by the non-profit Bat Conservation International) looked at 12 plots of corn in Illinois during the growing seasons of 2013 and 2014. In 6 of the areas, the researchers erected huge netting enclosures every night, keeping the bats at bay. In the other 6, bats were allowed to go about their batty business. The researchers found that the plots of land that were prevented from having bats had roughly 60 percent more corn earworm larvae gnawing on the ears of corn. The non-bat plots also had more fungus growing on the corn.

And while one corn fungus, known as corn smut, is slowly turning into a delicacy in some places, for the most part farmers would prefer their crops be pest and fungus-free.

Despite playing such a large role in agriculture, bats are the most endangered land mammal in North America. Luckily, there are plenty of promising efforts to save bats from disease and human activity, which is good news, not just for the bats, but for anyone who loves popcorn or corn on the cob.

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Last week, a swarm of 150 bats was released near a cave complex in Hannibal, Missouri. Each of the furry fliers was a medical marvel–they were survivors of the devastating fungal infection known as White-Nose Syndrome, which has killed millions of bats since it emerged 10 years ago.

But the fungus, named Psuedogymnoascus destructans (Pd for short) appears to be vulnerable to a very common bacteria, Rhodococcus rhodochrous found in soils. In a bacteria versus fungus showdown, the bacteria wins by releasing volatile organic compounds, creating an environment that prevents the fungus from growing.

Scientists working at Georgia State University identified the potentially healing properties of the bacteria back in 2012, while looking at bananas.

“Originally, we were investigating the bacteria for various industrial activities,” lead researcher Cornelison told Mother Nature Network. “In some of those earliest experiments, in addition to delaying the ripening of bananas, we noticed the bananas also had a lower fungal burden. I was just learning about white-nose syndrome at the time. But I thought that if this bacterium could prevent mold from growing on a banana, perhaps it could prevent mold from growing on a bat.”

Pd is so destructive to bat communities because it attacks when the bats are hibernating. The fungus grows over the nose and mouth and through the body, an invasion that wakes the bat up. Once roused, the bat uses up a lot of the fat and energy that it stored up over the warmer months, causing it to die of some horrendous combination of starvation, dehydration and exhaustion before it can replenish itself in the spring. Because most bats reproduce slowly, it is hard for bat communities to rebuild after being infected.

The researchers collected infected bats from hibernacula (places where animals like bats hibernate) in Missouri and Kentucky. The sick bats were sedated and placed in coolers that also contained the bacteria. The bacteria produced compounds that stymied the growth of the fungus, and all recovered, to varying degrees. The healthiest 150 were released in Missouri last week. Work will continue to see how these bats fare in the wild, and whether the method can be expanded to additional caves in the future.

Other research groups around the country are also working on solutions that range from using a kind of bat probiotic to boost bats’ immune responses, adapting AIDS treatments to combat the effects of the fungus, and even engineering solutions that allow researchers to keep track of the fungus’ spread.

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There are wildlife refuges in all 50 states and territories protecting animals both on the land and in the water. But what about up in the sky?

Plenty of birds, bats, and other flying creatures die every year either by slamming into buildings or getting hit by turbines and plane engines. Collisions between nature’s aviators and human machines led three scientists to write an article in Science, encouraging the creation of wildlife refuges in the sky to protect habitats in the air–not just on the ground.

The researchers are worried about buildings, turbines, power lines, antennae, aircrafts, helicopters, and drones. Wind turbines can be a particular problem for bats, as the animals confuse the large structures for trees and get whacked by the spinning blades. Birds, on the other hand, face threats like getting vaporized by solar farms and being sucked into plane engines.

But before we can create a safe haven for birds and bats in the sky, scientists have to figure out where they are flying. Migratory patterns are pretty well-known for many species; everyday flying patterns, where birds are just going about their normal routine, are less documented.

Once we figure out which areas of airspace are most useful to these animals, conservation groups can better draw up guidelines for where to build (or not build) structures that pose a threat to the flying critters.

“If you know all the species that use that area before you build an airport or a building or a wind farm, you will probably be able to reduce a lot of the conflicts,” Sergio Lambertucci, an author of the Science paper, told the BBC.

As for flying threats, like drones, the answer could be a no-fly zone over sensitive areas. A recent study showed that birds don’t mind drones that keep their distance and don’t approach them from directly overhead. But as Fast Company points out soon there could be more than a million drone flights over the United States every day as retailers figure out how to utilize the technology. (Gryzzlbox anybody?) There’s no guarantee that all drone operators will be respectful of the animals in the sky.

The National Park Service already has a ban in place forbidding the use of drones over national park land, citing in part, the safety and comfort of wildlife.

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A bat that may soon be added to the Endangered Species List could interrupt plans for a new oil pipeline in the Midwest. The proposed Sandpiper oil pipeline, intended to carry crude oil from South Dakota to Wisconsin, is nowhere near as big or controversial as Keystone XL. But it’s another flash point in the fight between sensitive wild animals and the oil and gas industry.

The potential pipeline would run 150 miles through the habitat of the northern long-eared bat, which has been decimated by white nose syndrome. Federal officials are about to determine whether it should be listed as threatened or endangered, after a series of meetings and public-comment periods last fall. Their deadline is April 2, but officials think the decision might come sooner, according to a report by Minnesota Public Radio.

This little bat, which is about the size of a one-dollar coin and weighs just 5 to 8 grams, used to be commonplace in the northeastern US. But white nose syndrome has killed about 99 percent of the population, the US Fish and Wildlife Service said in conference calls last fall. The bats hibernate in caves during winter, where they can easily spread the fungus that causes white nose. In the spring, they migrate 50 miles through forests to roost in trees, where the females give birth. The mothers go out at night to hunt insects, and the pups stay in trees until they can fly.

The pipeline would require removing some of those trees, so if the feds declare the bat as endangered or threatened, the project might be delayed or forced to choose a different route that avoids them. The company building the pipeline started its own study to examine the bats’ habitat, and has already modified its planned route, according to MPR.

They’ve also turned up some more intriguing findings — they argue the bats are more common than wildlife officials thought. From MPR: “The study’s nets caught hundreds of bats of various species. Long-eared bats were the most common, even more than little brown bats, which the DNR lists as the most common bat in Minnesota.”

Based on those findings, the Missouri Department of Natural Resources applied for a grant to do more research through this summer. Meanwhile, the oil company, Enbridge, is sharing its findings with wildlife officials. Will the company’s data show the bats don’t need protection?

All this comes on the heels of not only the Keystone XL debate, but a 50,000-gallon oil spill into the Yellowstone River Jan. 17. The river flows north from the national park to North Dakota and is a source of drinking water for some nearby towns. The EPA called it a “significant spill” not only because of its effect on human populations, but wildlife, too. It’s worth noting that bats, which fly and don’t live on the ground, can be just as affected by oil production as any other animal.

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For butterflies, distinguished wing markings can be great for confusing predatory birds, either by scaring them or by luring them away from vital body parts. Now, it turns out that moths, the nocturnal cousins of the butterfly, may use a similar strategy to deflect attacks. But since moths’ predators rely more on sound than sight, some moth species seem to create acoustic signatures that confuse bats.

Trailing behind its hindwings, the luna moth has two tails that extend for about an inch and a half. For a while, scientists weren’t really sure what purpose they served, since the moths can fly fine even with the tails removed. Back in 1903, one scientist proposed that the tails might serve as a diversion–that perhaps they create an acoustic signature that looks like wings in a bat’s echolocation, luring the attack away from the vital areas and out toward the disposable appendages. A paper published this week in Proceedings of the National Academy of Sciences provides the first evidence in support of this theory.

Video: Scientists think the luna moth’s flopping tails may look like wings in a bat’s sonar, serving as a decoy target.

To put the theory to the test, a research team from Boise State University, University of Florida, and Northeast Ohio Medical University pitted 162 luna moths against eight brown bats. Half of the moths had their tails removed. In a dark room, the researchers used fishing line to string moths from the ceiling, three at a time: a luna moth with its tails intact; a luna moth with its tails removed; and a moth from a tailless species, as a control. Then they set a bat loose, while high-speed infrared cameras and ultrasonic microphones recorded the interactions.

In the end, the bats captured 81.3 percent of tailless luna moths, compared to just 34.5 percent of luna moths who kept their tails. The researchers calculated that tailless luna moths were 8.7 times more likely to get eaten.

When bats attacked luna moths with tails, they aimed for the tail 55 percent of the time. But when they did aim for the tails, they were successful at capturing the moths only 4 percent of the time. The findings support the theory that moths’ tails serve as a decoy to deflect bat attacks.

Video: When bats aim for the luna moth’s tails, the moth escapes 96 percent of the time.

Another possibility is that some moth species developed tails as a result of sexual selection—that is, females thought the tails were attractive, so males developed longer and longer tails over time. This hypothesis is less likely, the researchers say, because nocturnal moths don’t typically use visual cues to choose mates, and because the females are not particularly choosy; they usually mate with the first male that finds them.

Doing a phylogenetic analysis, the researchers found that tails evolved independently four different times across several clades of moths, underlining the importance of the mysterious appendage.

Up next, the researchers are interested in comparing these different clades of tailed moths, to see if moths with longer tails are better at evading capture and damage than the moths with shorter tails.

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Kevin Keel would rather not infect bats on purpose. A veterinary pathologist at the University of California at Davis, he studies white nose syndrome, a disease that is decimating bat populations across the United States. To do it, he needs to take tissue samples from healthy bats and study them later in the lab.

But how to collect the samples? Biologists can catch a bat and snip a slice of wing with a hole-puncher of sorts — but this is really tricky. Keel and colleague Barbara Shock, a wildlife disease ecologist at UC Davis, needed a simpler, specialized device that any biologist can use.

They turned to the university’s 3-D printer lab for help, and its manager suggested they ask the students. The problem turned into a student engineering competition held in mid-January. During a frantic 30-hour Make-a-thon, student teams came up with designs, sketched them in computer-assisted design software, and built them on 3-D printers.

“To understand this disease, we really need to be able to do experimental infections,” Keel says. “But we’ve already lost so many bats, and it’s so difficult to work with bats in artificial hibernacula, that we were looking for another approach that would be powerful.”

White nose is caused by a fungus, Pseudogymnoascus destructans, which colonizes the bodies and wings of cave-hibernating bats. Scientists aren’t totally sure how it kills them, but one theory is that bats wake up from hibernation to groom themselves too frequently, depleting their fat reserves and starving to death. Keel studies how white nose spreads by inoculating bat skin samples, called tissue explants, with the fungus.

This means cutting a piece of wing tissue in the field, and simultaneously stretching it across some sort of adhesive membrane. This is tough work — imagine holding a tiny, squirming, bitey bat and trying to clip part of its wing without damaging it.

“A bat wing is so thin and so elastic that it’s like wet toilet paper, and you can never get it to go back into its native shape,” Keel says. “You can imagine how frustrating it is to hold the bat on the cutting board, pull the bat wing, and if you are sampling for diagnostic purposes, trying to see where the fungus is with ultraviolet light. We wanted something that would make it ultra simple that we could use with one hand, allowing someone to restrain a bat with one hand and snip a biopsy with the other hand.”

Keel and Shock pitched their problem to 60 student members of UC Davis’ Biomedical Engineering Society on Jan. 16, and the students worked around the clock to draw designs and build CAD files for each part.

“They came up with some designs that would not have occurred to us,” Shock says.

Explant Sampler

One successful prototype, seen above, has a special medical-grade adhesive ringing one side of the part labeled “b.” When this device used to punch a small hole in a bat wing, the wing membrane is stretched over the adhesive, securing it in place. Its design allows one side of the bat tissue to be immersed in cell medium, keeping the tissue alive, while the other side is exposed to the air — and the white nose fungus.

By Sunday evening, Jan. 18, the Makeathon yielded four projects that could actually work in the field. Keel and Shock are now working with the university’s TEAM Design, Prototyping, and Fabrication Facilities to refine and then build lots of them.

Bats live in dark, inaccessible caves or high in trees; they fly; and they communicate in ultrasonic chirps that we can’t hear, so they can be among the toughest animals to study in the field. Biologists often turn to unique tools for tracking them. But the competition made it unique, Shock and Keel say. What’s more, the engineers learned about something they otherwise wouldn’t know, Shock says.

“All of these 60 participants had to learn about white nose syndrome and why bats are important,” she says.

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About 25,000 to 3,000 years ago, land mammals died out in massive numbers from the Arctic to the Caribbean, which scientists have attributed variously to climate change and human activity. Bats weren’t as susceptible as their non-flying cousins — in the Caribbean, about 18 percent of bat species died out, compared to about 80 percent of land mammals — but still, several species disappeared from entire islands.

Without good radiocarbon-dating evidence, it’s been difficult to peg just when these die-offs occurred, which makes it harder to pin down what caused them. But a new study says it was probably our fault.

This challenges previous research that suggests natural climate changes were a culprit. Earth 25,000 years ago was a cooler place, with huge amounts of water locked up in glaciers. As temperatures increased in the transition between the Pleistocene and Holocene eras, the glaciers melted and the oceans rose, turning big islands into small islands and shrinking animals’ habitats.

J. Angel Soto-Centeno of the American Museum of Natural History and David Steadman, a University of Florida ornithologist, set out to unravel this story. If extinctions were driven by climate change, they would expect to see radiocarbon-dated fossils of extinct bats from the era known as the Pleistocene-Holocene Transition, and paleoclimate evidence should clearly show changes in available habitat — like the submergence of caves.

They excavated bat wing bones from a cave on Great Abaco, an island in the Bahamas, and dated them along with more than 2,000 bat fossils from 20 different sites in the Caribbean.

Hunting for Bat Fossils

“Ours are the first radiocarbon dates for bat fossils in the whole West Indies,” says Steadman, curator of ornithology at the Florida Museum of Natural History, in a statement. “The new dates prove that certain bat populations were still in existence much later than previously thought — around the same time humans arrived.”

He and Soto-Centeno found at least five bat species withstood warming temperatures and reduced land areas, but were wiped out much later when climate conditions were much like they are today. “If climatic changes during the PHT were the primary driver of the losses of Caribbean bats, it is difficult to understand why these species survived for at least 5,000 years before becoming extinct,” the authors write. “Late Pleistocene changes in the size and distribution of Bahamian caves and cave environments are unlikely causes for the extirpation of these populations.”

Instead, they were done in by humans encroaching on their habitat. This likely was most prevalent in the forms of early farm settlements and their affect on wildfires, the authors say.

Bats are still prevalent throughout the Caribbean — they’re the dominant mammals in the entire region, as the authors point out. So why is this important? Understanding how, and when, certain Caribbean bats went extinct helps scientists understand how animals adapt to changing environments, and which ones might do it better than others. This can help biologists save modern animals from meeting similar fates in the face of climate change — which, this time, is also our fault.

“Now we have good evidence that it is not the shrinking of islands that wiped out these populations, and the only thing we know happened in the last thousand years that might affect bat populations is the arrival of people,” Steadman says.

The paper is published in Nature Scientific Reports.

DOI: 10.1038/srep07971

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When the guy in the cubicle next to you microwaves his tikka masala or tears open a bag of chips, your nose and ears perk up — food. Your senses trigger your brain to, maybe, head for the break room searching for a snack of your own, or even steal some of his chips. (Or maybe you just get annoyed and tell him to eat elsewhere.)

For bats, the sounds of others’ eating is a benefit, not an annoyance. Bats follow other bats’ signals to find food of their own, a recent study says.

“When you sit in a dark cinema theater and someone opens a bag of chips, everyone in the theater knows that someone is eating chips and approximately where that someone is,” says prolific bat researcher Yossi Yovel of Israel’s Tel Aviv University, in a statement. “Bats work similarly.”

Bats evolved echolocation to help them hunt, a unique ability rare in the animal kingdom. But it’s good for more than just the bat that’s using it. Other bats can eavesdrop on their companions’ echolocation calls, using them to zoom in on a food source they otherwise might have missed.

Yovel and colleagues developed tiny GPS trackers capable of recording ultrasonic calls. They attached these to greater mouse-tailed bats (Rhinopoma microphyllum), which roost in huge colonies numbering into the thousands and often hunt as a group. They found that bats tended to stick together while foraging for food, staying within 150 meters (about 490 feet) of other bats 40 percent of the time. This happened even though such close proximity could hinder the hunt.

When too many bats flew close together, foraging wasn’t as successful, suggesting bats were interfering with each other’s sonar. They weren’t jamming each other, exactly, Yovel and colleagues write. It’s more like they were crowding each other out. Instead of chirping to find insect prey, bats had to echolocate each other to avoid collisions. “Such dense situations would probably require sensory attention, making the detection of tiny insects difficult for short periods,” they write.

So why would they continue to stick close together? Echolocating bats constantly chirp ultrasonic calls, which get faster as a bat closes in on an insect. All these calls provide constant information, allowing the bats to effectively work as a sensor array, Yovel and colleagues write.

A single bat’s sonar can track objects within about 10 meters (32 feet), but a bat can hear another bat’s sonar from 160 meters (525 feet) away. So eavesdropping improves a bat’s hunting ability, even though it might have to employ some temporary aversion tactics to avoid crashing with other bats.

This a sensory trade-off is probably not unique in the animal kingdom, the authors note. In birds that search for seeds on the ground, the visual detection range of a seed is much shorter than that of seeing a pecking fellow bird, they write: “Birds can thus gain from searching together.” Maybe that’s why we’re so finely tuned to hearing when someone else is eating.

The paper was published in the Jan. 8 issue of Current Biology.

Citation: Current Biology, Cvikel et al.: “Bats aggregate to improve prey search but might be impaired when their density becomes too high.” DOI: 10.1016/j.cub.2014.11.010

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Although they fly like other bats and look like other bats, fruit bats lack the special biosonar that makes their smaller kin so unique. About 85 percent of the 1,200 known bat species emit ultrasonic chirps and clicks to hunt, but the other 15 percent, the megabats or “Old World fruit bats,” don’t do this. They don’t have any of the special adaptations it requires.

But fruit bats echolocate nonetheless, according to a new study. They just do it using their wings, not their lungs. While this rudimentary form of echolocation isn’t great, wing clicks help the bats distinguish big objects.

Yossi Yovel and Arjan Boonman of Tel Aviv University in Jerusalem recorded 19 individuals from three fruit bat species, listening for clicks while the bats flew in complete darkness and while they flew in light. Their clicks increased 3- to 5-fold in the dark, and they were able to find their way — but they weren’t very good at it.

To test the bats’ abilities, the researchers strung up some three-quarter inch diameter cables in a room; that’s about 100 times the thickness a microbat (a sonar-producing bat) could sense. The bats kept crashing into the cables. Then Yovel and Boonman tried a somewhat easier test, having the bats discriminate between a black board, which reflected sound well, and a think black sheet that reflected much less sound. The bats were supposed to land on the board, and they picked this up quickly enough that the researchers were satisfied they were using echolocation.

Scientists tried anything they could think of to stop the bats from clicking, including sealing the animals’ mouths, numbing their tongues and taping foam on their forearms.

“The ability of the bats to perform this task proves that they are capable of using biosonar to detect, localize, and discriminate large objects,” they write.

Yovel and Boonman were surprised that all the bats clicked, and that the clicks were produced by the wings, they say: “Arjan and I still find that hard to believe,” Yovel says in a news release.

To make extra sure they were getting it right, the researchers tried anything they could think of to stop the bats from clicking — including sealing the animals’ mouths, numbing their tongues and taping foam on the bats’ forearms. “But nothing stopped them from clicking, except for when we interfered with their wing flaps,” Yovel says.

They’re still not exactly sure how the bats make the clicks, but they hypothesize that it could involve two parts of one wing touching each other, a wing slapping the bat’s body, or snapping the wing’s bones. Birds have been observed doing these things, they note.

Why would big bats evolve this rudimentary capability? Wing-based echolocation may have similar roots to larynx-based echolocation: Finding your way in a dark cave. One species the researchers studied, the cave nectar bat (Eonycteris spelaea), often has to fly in complete darkness to reach its roost. This bat also had the highest wing-click rate. Another bat, the greater long-tongued fruit bat (Macroglossus sobrinus), lives in trees and flies slowly, so it has more time to look around and avoid a crash. It had lower click rates than the other bats in the study.

Scientists know echolocation has already evolved at least three times — in bats, toothed whales, and some birds — and maybe as many as five times, if you include tenrecs and shrews. But this study suggests it may have evolved more than once in bats alone, the largest group of mammals.

“Clicking fruit bats could be considered behavioral fossils, opening a window to study the evolution of echolocation,” the authors write.

The paper is published in Current Biology.

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When you step out of an elevator, how frequently do you know — intrinsically, without thinking — which way to turn?

For some people, especially those who ride up steel cages every morning to an office, correct orientation is automatic. Others have to think about which way to go, and might awkwardly bump into our elevator-mates as we turn. In either case, we’re using intrinsic navigation. A new study of bats explains how our brain cells help with this, directly responding to horizontal or vertical orientation and acting as an internal compass.

Navigation requires two things: knowing where you are, which is like having a map, and knowing which direction you’re facing on that map, like having a compass. Mammals need to process lots of this information to safely navigate our environments, from humans jostling through a crowded elevator foyer to moles burrowing underground to bats winging through trees.

Previous work on rats identified a brain center that helps with all this. It’s located in the dorsal presubiculum of the hippocampus. These so-called “head-direction cells” help rats, bats, cats, dolphins and other mammals orient themselves, according to several previously published studies. But nobody had studied what happens in the brain to orient all three head directions at once — up, down and to the side.

Arseny Finkelstein and colleagues at the Weizmann Institute of Science in Israel set out to do this, and they focused on the dorsal presubiculum of the Egyptian fruit bat. They attached wireless devices to measure the brain activity of bats crawling around in search of food, and also measured which way the bats were moving in three dimensions, so they could correlate the bat’s actions with its brain activity. They also monitored bats flying toward a perch where they would land head-down. This is a tricky maneuver — imagine a bat flying toward a perch, with its body and wings facing forward. As it comes in for a landing, it flips itself onto its back, so to speak, and thrusts its legs upward. It ends with its head facing down and facing the direction from which it came, a whirl that would make most of us dizzy.

Watching the bats’ brain activity, the researchers noticed certain cells responded to horizontal orientation, and others to vertical orientation. Together, the cells help the bats track their orientation in all three dimensions of space. Instead of a sphere, which was the researchers’ first guess, the head-direction cells take on a toroidal shape — they look like a thick donut, which the researchers dubbed a “3-D neural compass.” How would this compass work? As a bat rotates its body, nerve cells in its brain gradually move around the donut. They activate in a pattern that represents the bat’s direction.

The same researchers also recently reported 3-D place cells in the brains of bats, and they think these groups work in concert — one is a map, and one is a compass.

Other animals might have neural compasses that are more spherical in shape, which would also keep track of an animal’s direction in a lateral roll, the authors note. But bats don’t really do that, so the donut shape fits them just fine. More work has to be done to describe similar systems in other mammals, but the researchers think they’re likely not limited to bats.

“We predict that conjunctive 3-D head-direction cells might be found also in non-flying mammals that move in complex 3-D environments or that orient their head up/down, such as squirrels, cats, dolphins and primates,” they write.

The paper appears online today in Nature.

DOI: http://dx.doi.org/10.1038/nature14031/

Egyptian Fruit Bat Hanging

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Sleep deprivation saps much more than your energy. Studies show it also weakens your memory, changing the way we convert short-term memories into long-term ones. But not for bats.

This time of year, millions of bats from a spectrum of species are hunkered down in caves, where they’ll huddle together for warmth and hibernate through the winter. (Wouldn’t that be nice?) But hibernation, during which bats enter a suspended state called torpor, is not the same as sleep.

Hibernating animals don’t truly shut down for the season. They lower their body temperatures and slow their metabolic rates and heart rates, a state known as torpor. This is an extreme change — the resting heart rate of a bat is about 300 to 400 beats per minute, depending on the species. When in torpor, this drops as low as 10 bpm, depending on the species and the external temperature, says the Organization for Bat Conservation.

But hibernating animals have to emerge from torpor once every few days to move around, maybe eat some stored food if that’s their thing, pee and poop. Then they reenter torpor. This on-again, off-again pattern is what characterizes hibernation. Squirrels are among the species that do this, nibbling stored food during their waking times. Bats also do this, though they don’t have any insects to eat.

When a mammal is in torpor, it gets less rapid eye movement (REM) sleep and less slow wave sleep, because good sleep involves some physiological processes that require warmer body temperatures. Animals sleep a lot when they emerge from torpor, with brain activity patterns demonstrating signs of sleep deprivation, according to the authors of a new study on bat memory.

Nursery roost of greater mouse-eared bats

In animals like squirrels and hamsters, this sleep deprivation means loss of spatial memory and the ability to recognize objects, according to previous research. Ireneusz Ruczyński from the Mammal Research Institute in Poland wanted to see how well bats’ memories fared.

He and his colleagues conducted two experiments on some greater mouse-eared bats from Bulgaria. These animals are so tiny — between 20 and 45 grams — that they enter torpor every day when temperatures reach a certain threshold. This helps them conserve energy for the high cost of flying to find food.

The first experiment required the bats to learn the location of food, which was emphasized with a food reward. The second required them to learn the location of a dry perch mounted above a half-centimeter of water — this entailed remembering an escape route from an “uncomfortable situation.” After training sessions each day, the scientists let the bats rest, with one group remaining at a balmy 22 degrees Celsius (71 F) and another group at 7 degrees Celsius (44 F).

The researchers assumed that bats kept at a warmer temperature between training and test sessions would show faster learning over several days, because they’d be spending less time in torpor. But there was no difference between the groups.

“The extremely weak tendency for slower learning in bats kept at lower temperatures suggests that if torpor indeed affects learning abilities, it is happening at a very subtle level,” Ruczyński and colleagues write.

Myotis myotis, the mouse-eared bat

So what can we learn from the flying mammals?

Bats live for a long time in complex environments that require them to maneuver around each other and different objects. Remembering information about their environment is probably important for their survival, Ruczyński and colleagues write. They must have evolved behavioral and physiological techniques to balance their trade-off between energy savings — torpor — and cognitive impairment, they say. In this study, just an hour or two at high body temperatures was enough to convert short-term memories into long-term ones.

“Although solving cognitive problems demands high brain temperatures, a period of decreased body temperature and inactivity does not necessarily impair cognitive processes that are actively underway before and after torpor,” they write.

Could this be good news for the first human crews sent to Mars? Maybe, although a lot more work needs to be done. For now, it’s just good news for the bats.

The study appears in the Journal of Experimental Biology.

Reference: Ruczyński, I., Clarin, T. M. A. and Siemers, B. M. (2014). Do greater mouse-eared bats experience a trade-off between energy conservation and learning? J. Exp. Biol. 217, 4043-4048.

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They’re not the best leftovers, but winter vegetables are worth making well beyond Thanksgiving — think squash, cauliflower, and brussels sprouts. If you don’t like brussels sprouts, you’re just wrong. It could be because you don’t like their bitter taste, though.

That could mean you’re not cooking them properly, or it could mean you’re a “supertaster,” able to detect flavor differences that wouldn’t register with the rest of us. So if you have an amped-up ability to taste bitterness, you are the opposite of a vampire bat.

They’re the only mammals to feast exclusively on blood, a strange characteristic that often gives all bats a bad name. But this dietary choice might have made vampire bats bad tasters, according to research published earlier this year.

Vampire bats have fewer bitter taste receptor genes than other bats which eat insects, fruit and nectar. Bitterness sensitivity is a strange trait to lose, because it gives animals an evolutionary advantage.

In human supertasters, about 25 percent of the population, a heightened sense of bitterness has been linked to an ability to fend off respiratory infections. A study published in 2012 found that supertasters have a particular bitter-taste receptor in their noses that helps their bodies fight off sinus infection. The receptor activates cilia, the tiny hairs in your nose, and increases production of nitric oxide, both of which help force out and kill bacteria. Supertasters also avoid overstimulation by sugar, salt and fat, which means they’re less likely to become obese or develop cardiovascular or other metabolic diseases.

In humans and other animals, bitter sensitivity evolved as a protection mechanism — bitter things are often poisonous. If you bite into a potato and it tastes bitter, don’t eat it. Not all animals can sense bitterness, though — dolphins, for instance, eat their fish whole and have no bitter taste-receptor genes.

But other bat species have lots of these genes, and bats share a much more recent common ancestor with each other than they do with dolphins. So why would vampire bats lose this ability?

They don’t need it, according to Huabin Zhao from China’s Wuhan University and colleagues. Because vampire bats drink only blood, they wouldn’t eat the toxic plants and animals that helped bitter-sensitivity evolve in other mammals. They also place a higher priority on their other senses, which can help them find food. Vampire bats use their sense of smell to detect predators, they use echolocation to find prey, and they use infrared sensors to locate small blood vessels that offer a nice place to snack.

During a previous study, Zhao found the bats were indifferent to sweet and umami flavors, too. Their indifference to bitterness matches with the researchers’ genetic analysis, which found several of the bats’ bitter taste receptor genes were “pseudogenes,” meaning they didn’t serve any biological function.

To explain why they have any taste genes at all, Zhao hypothesizes that the bats’ ancestors might not have eaten blood, and that their dietary changes might have come about more recently in evolutionary history. And the small number of working bitterness receptors might play some other role in bat physiology — just as they do in us.

Vampire Bat Says Yummy

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As the sun set over the mountains near Jinan, China, Nicole Abaid sat by the narrow mouth of a cave and watched a colony of bats emerge. Unlike the radar that humans use, the bats’ echolocation didn’t seem to jam as the animals converged into a thin stream. Abaid, a mechanical engineer and mathematician at Virginia Tech, was there to discover why—an insight that could lead to more intelligent robots.

After getting her start by studying how schooling fish come to consensus, Abaid has broken new ground with bat colonies. Bats can adjust their signals so they don’t overlap with their neighbors’ frequencies. Abaid suspected they may be able to share information too, so she modeled how they might listen in on each other to better avoid obstacles. She went to China to line the bat cave with infrared cameras and an ultra-sonic mic that could gather data to verify her model. “The big idea is to tell if and how they use each others’ signals,” she says. At the same time, she’s designing bat-inspired ultrasonic sensors to improve communications among robots.

Ultimately, Abaid hopes to imitate how animals elegantly overcome challenges like radar jamming—research that could some day help us manipulate man-made swarms, such as underwater vehicles that rely on sonar. “Learning about how this biological system works could help us design how we control engineered systems,” she says.

This article originally appeared in the October 2014 issue of Popular Science.

_Click here to read about the other Brilliant Ten honorees of 2014. _

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Of all the strains of the Ebola virus, the Zaire strain (Zaire ebolavirus) is the deadliest. That’s the species now infecting people in Guinea, Sierra Leone and Liberia; in the ongoing outbreak, it’s killed more than half of the people who contracted it.

Yet before this outbreak, nobody had ever seen Zaire ebolavirus in West Africa. Zaire Ebola was known only to crop up in the Democratic Republic of the Congo, the Republic of Congo, and Gabon in Central Africa. So how did the virus travel those hundreds of miles to Guinea, where the current West African outbreak began?

As fun as it is to blame Gwyneth Paltrow, it was not her (character) this time. In the 2011 movie Contagion, Paltrow played “Patient Zero” in a deadly flu epidemic. Her character’s jet-setting ways helped the contagion spread. Yet scientists think it’s unlikely a person sick with Zaire Ebola boarded a plane in Central Africa and carried the illness to Guinea. Those first cases occurred in remote regions that are difficult to reach. “A human would have to travel a long distance” to get there from Central Africa, Daniel Bausch, a doctor who studies tropical viruses at Tulane University, tells Popular Science. Plus, scientists would expect to see an outbreak in Central Africa just before Zaire ebolavirus showed up in Guinea, which didn’t happen. (That doesn’t mean travel does not play a role in Ebola’s more local spread now.)

Instead, scientists are now considering a couple of possibilities for the origin of West African Zaire ebolavirus. One is that it has long circulated there, but scientists never noticed it. Another is that it was carried there from Central Africa by a yet-unknown species of bat— but exactly which species is a big question. Bausch is publishing a paper today, in the journal PLOS Neglected Tropical Diseases, that reasons through these possibilities.

What was that very first person doing when they got infected?

It will take further research to sort out which explanation is the likeliest, and that research may not happen for a little while yet. For now, experts are focused on caring for those who are sick and preventing further spread. In the future, however, researchers will likely examine wild bats in Guinea, as well as blood samples collected from people from before the outbreak. They’ll be looking for that first instance of when Zaire Ebola crossed into a human being.

“What was that very first person doing when they got infected?” says Jonathan Towner, a virologist with the U.S. Centers for Disease Control and Prevention. “If we can identify the natural reservoir, then, as we’re doing for Marburg virus, you can advise the public on how not to get exposed.”

Marburg and Ebola are closely related, since they are in the same family of viruses. Like Ebola, Marburg causes hemorrhagic fever and can be deadly. In 2009, Towner and a team of scientists from Uganda published a paper confirming a species of fruit bat called Rousettus aegyptiacus harbored Marburg viruses. It was a feat of patience, for one thing. It required the capture of hundreds of bats, as only 2 or 3 percent of them carry the virus at a time.

The discovery about Marburg meant health departments could warn tourists and locals about wearing masks and other protective gear when entering caves home to Rousettus aegyptiacus. That said, such interventions have to be affordable for those who need it most. Miners in Sub-Saharan Africa often work in caves with rousette bats, but they usually can’t afford expensive protective equipment.

“We have to be realistic. This is happening in the poorest areas in the world,” Bausch says.

Because Marburg and Ebola are so closely related, the finding about Marburg also helped narrow down the search for animal carriers of the West African Zaire ebolavirus to bats. That’s an improvement on what scientists were doing 20 years ago. “We were trying to find it by trapping all sorts of things,” Bausch says. “Mosquitoes, monkeys, spiders, rodents and everything.”

It’s Ebola’s likely persistence in bats—its ability to circulate quietly among forest animals in between outbreaks in humans—that makes it seemingly “emerge from the forest” at random, Bausch writes in his new paper. One of his major points, however, is that such emergences aren’t random. They happen in places where wars have broken down the public health measures that help contain Ebola, which is, after all, difficult to transmit between people.

“These are populations and countries that are vulnerable to the propagation of this virus,” he says. “I think it is worth recognizing that the social and economic background of this is equally important as the biology of the virus that’s emerging from the forest.”

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What Bat Is That?

Deep within the labyrinthine interior of the Field Museum of Natural History in Chicago, at the end of a cluster of corridors and stairwells, Bruce Patterson stands amid a collection of more than 58,000 bat specimens. The collection at the Field is a microcosm of natural history, told in bats.

Patterson strides from one bay of drawers to the next, naming the genera and species contained within each stack. Stopping at random, he opens a drawer: an array of bats from the Neotropics, laid out like a squadron. Each bat is reduced to a stuffed pelt, its wings outspread as if mid-flight, and a vial containing its cleaned skull and mandible. Many of the specimens were obtained more than 60 or 70 years ago by intrepid field biologists like Patterson in far-flung locations like Nepal, Somalia and the Philippines.

Many bats were netted in rainforests, or plucked from the roofs of caves like strange fruit. Occasionally, bats were simply shot from the sky. Browsing through the drawers, one still can find specimens that were brought down with birdshot, pellet holes in the dried papery skin between wing bones.

Every bat is tagged with a label identifying it by species, the date and location it was collected, and the name of the biologist who collected it. The integrity of the entire collection depends on the simple fact that every bat belongs to the species name on the tag affixed to its ankle, sometimes handwritten in spidery cursive that predates both Patterson and me.

But what if a specimen does not belong to the species written on its label? What if the collection is wrong? Patterson’s recent work, published last year in the journal Molecular Phylogenetics and Evolution, suggests that this might be the case. Such a finding has far-reaching implications. What if, upon closer examination, other specimens can be separated too, divorced into a constellation of interrelated but distinct species? What if, in fact, almost nothing is really what we think it is?

Sturnira lilium: the little yellow-shouldered bat. A medium-sized, fruit-eating bat with distinctive yellow-brown oval patches on its shoulders. At the end of its blunted muzzle, a spear-shaped nose-leaf points vertically into the air, as if balancing an inverted heart there. It is one of the most common Phyllostomid bat species in the New World tropics, found all the way from Sonora and Tamaulipas in northern Mexico, through Central America, and southward to Argentina and eastern Brazil. It occupies an enormous bell-shaped footprint. Except, says Patterson, that it doesn’t.

Bat Bones

Instead, Sturnira lilium — regarded for decades as a single, well-defined species — is a complex of seven different species, each occupying its own circumscribed range. “It turns out that Sturnira lilium is actually restricted to the Brazilian shield of Brazil, Paraguay, and Argentina,” says Patterson. Ironically, almost none of the researchers who have studied Sturnira lilium — either in the thin air of the Andes, or beneath the wet green canopy of the rainforest — have actually seen one. “All of the literature actually corresponds to a different species of bat,” says Patterson. “The behavior, the dietary studies, the ecology, the parasites: all of that needs to be revised.”

And that can be difficult. Increasingly, field biologists like Patterson are using novel techniques to identify new species, recategorize known species, and to study speciation — how a species becomes a species.

Suddenly, Sturnira has become the single most diverse Phyllostomid bat genus in the Western hemisphere.

Patterson and his graduate student Paul Velazco began by collecting specimens. Tissue samples came from multiple locations — more than one hundred and thirty specimens in all. Some were collected live in the field, in Central and South America by biologists. The majority — almost a hundred specimens — came from museum collections like the one at the Field: from across the United States; from Brazil, Canada, Peru, and elsewhere. Using molecular techniques, Patterson and Velazco compared DNA isolated from each Sturnira specimen, searching for subtle differences in its genetic code based on where it was collected.

“There are places where two species occur,” Patterson says, “but for the most part it’s like a jigsaw puzzle — one piece replaces the other and presumably serves the same ecological role that its counterpart serves in that adjacent real estate.”

In a moment, one species becomes seven. Three of them are completely new to science. Velazco and Patterson have scrutinized the specimens, describing them morphologically for a second paper recently submitted for review.

“Some occur up to four thousand meters in the Andes,” says Patterson. “It’s cold. It’s cloud forest habitat. And they’re really hairy. Whereas others are down in sweltering lowland forests, and they tend not to be very hirsute. There are differences like that. As soon as you see a skull, there are dental and cranial differences that also help to tell these apart.”

With these newly published data, the larger Sturnira genus of bats to which Sturnira lilium belongs has grown too, ballooning from a known handful to a wide, diverse group. “About 1960,” says Patterson, “there may have been four or five species of Sturnira bats. That eventually grew over the years to fourteen species in 2005. But with our study we’ve documented twenty-three genetic units that seem to bear the hallmarks of species.”

The implications are wide-ranging — and impossible to ignore. One of the previously undescribed species is found only in a narrow coastal territory that runs south along the Pacific seaboard from Colombia to Ecuador. As deforestation strips it of its habitat, it has become an immediate conservation target. Another species is limited to the Lesser Antilles, a chain of rocky volcanic islands in the Caribbean Sea. Suddenly, Sturnira has become the single most diverse Phyllostomid bat genus in the Western hemisphere.

Stuffed Bat

How many other species are nested like Russian matryoshka dolls within the name of another species they closely resemble? Perhaps other species mistaken for Sturnira lilium have already become extinct, disappearing even before taxonomists had the opportunity to describe them properly. It is unknowable now. Researchers have identified bat species on the basis of the parasites that inhabit them — different parasites preferring different bat species. These data can help them calculate how long ago each Sturnira species diverged from its common ancestor, creating an overgrown taxonomic tree that seems still to be growing.

“If you have more sensitive measures, you can invariably subdivide the range of wide-ranging and presumably abundant species,” says Patterson. “Often, what happens is that this wide-ranging thing that no one was worried about suddenly becomes three or four narrowly-endemic species that may occur on a small fragment of habitat remaining in their particular part of the original species range.”

Patterson pauses for a moment, perhaps considering the collection of thousands of bat specimens amassed behind him.

“It’s true for mice, for frogs, for fish,” he says. “It’s true for all sorts of organisms.”

Christopher Kemp is a scientist in Michigan. His most recent book is Floating Gold: A Natural (and Unnatural) History of Ambergris.

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Though whales, gibbons and even mice can produce songs, mammals typically aren’t capable of altering their song composition and structure in the way that songbirds can. Bats seem to be the exception to this rule, producing variable songs that sound a whole lot like birdsongs. The nocturnal mammals, notorious for relying on their ears rather than their eyes, use singing to attract mates, rather than the visual cues typical of other animals, like brightly colored feathers.

Over a period of three years, Texas A&M biology professor Mike Smotherman recorded the calls and songs of the thousands of free-tailed bats roosting in the university’s football stadium. He found that male bats can be pretty creative when it comes to their serenades, creating different singing styles.

The seductive croons of free-tailed bats have a syntax and structure with different types of phrases and syllables, one that can alter songs based on the social context. The bats alter their phrases to produce new styles.

Chirps And Trills

When it comes to finding a mate, the bat has to get to the point, and quickly. A romantic bat flyby only presents an attention-grabbing window about one-tenth of a second long, so a male bat uses one specific song to get a female’s attention as she flies by his roost at 30 feet per second. Then, if she deigns to join him, he mixes up the songs to keep her entertained long enough to get down to business.

No romantic duets, though, unfortunately: Bat songs are an exclusively male domain.

The research is published in Animal Behaviour.

Nature World News

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In waging millions of years of battle, both moths and their predators, bats, have adapted certain evolutionary tactics to give their species the upper hand. Bats have a “stealth mode” of hunting, and some use clicks that are out of the frequency of moths’ hearing ranges to locate prey. Some kinds of moths, though, have one-upped them with a battle tactic that’s way cooler: defensive sonic genital blasts.

Researchers from Boise State University and the University of Florida studied how hawk moths, a family of moths found most commonly in the tropics, responded to the ultrasonic hunting calls of bats. Though their techniques are a bit different (for obvious reasons), both the male and the female in three different species of hawk moth seem to rub their genitals across their abdomens to produce their own ultrasound clicks, they found in a study online today in Biology Letters.

As Nature describes the process:

The males did so by rapidly grating stiff scales on the outer surface of their ‘claspers’ — structures normally used to grab females during mating — against part of the abdomen, the researchers report. Females also seem to pull part of their genitalia inwards so that genital scales rub against their abdomens.

They aren’t sure yet exactly how this genital clicking works as an anti-bat defense. It’s possible the ultrasound could startle or warn the bats off, or maybe even jam their echolocation, as one species of tiger moth does. It could be an instance of what the authors call “cross-family acoustic mimicry,” since the clicks are much like the bats’ own. In any case, it’s a neat bit of convergent evolution–the evolution of the same trait in different kinds of animals.

Fascinating moth genital video below:

Nature

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Bats are social animals, developing friendships and raising their young village-style. They also need to communicate like fighter pilots–quickly, specifically and in brief form–so they don’t collide when they’re hunting prey. And they need a way to relocate their social groups in the dark. The combination of these attributes led scientists to wonder whether bats, like humans, can recognize close social contacts based on the sounds of their voices.

Hanna Kastein from the University of Veterinary Medicine in Hannover, Germany, and her colleagues set out to study the the false Vampire bat, Megaderma lyra, and noticed that they perform little individualized “body contacts”–like pals tapping each other on the shoulder. The researchers wanted to see if these bats also recognized each other by voice, and whether this helps them find each other at night.

They took two groups of bats and put them in two separate “flight rooms” for two months. The scientists noted which bats were in frequent contact, and then separated them for up to four hours to see if they’d call each other. They recorded the bats’ name-calling, and then played these recordings to three sets of other, isolated bats: Known body-contact friends, non-body contact friends, and unknown bats from another group. Here’s an example call:

Kastein and colleagues found all the isolated bats turned toward the loudspeakers, apparently yearning for bat companionship. Then the team did a habituation exercise, in which they played repeated calls from one bat, until the test-subject bats started to ignore it. After that, they played a different set of calls. Bats were more likely to respond to a call from an existing friend-bat–a member of their own social group–than a new call from that original, habituation-bat, the researchers found.

This is important, because it suggests the bats noticed something about the sound of the calls that is apparently unique to individuals. They could discriminate among new bats, old bats and new sounds made by old bats.

“Bats are the first mammals for which this close functional relationship between stimulus structure and discrimination behavior has been established. Such a relationship may be relevant for mammals in general,” the researchers write.

Last year, some other German researchers studied bat echolocation calls–which humans can’t hear–and found these, too, contain detailed information about individuals. This vocal signature helps male bats avoid rivals and helps females find their partners, for instance. For bats as well as people, the ability to find your friends in a clamorous crowd can be useful.

The new research appears in the journal Animal Cognition.

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Nectar-feeding bats have the highest metabolism among mammals, burning half their body fat every day, and therefore they must eat pretty much all the time. To sip their food efficiently, the bats have evolved special tongue-hairs that help them grab as much sweet nectar as they can with every lick. This finding, made possible with high-speed video, could lead to potential new designs for medical equipment.

The bat tongues work like a mammal penis, engorging with blood to become stiff.The bat in this case is Glossophaga soricina, or Pallas’s long-tongued bat, which lives in Central and South America. Biologists already knew it had a hairy tongue, but they thought these fibers were passive, just hanging out when the tongue is lolling around, explained Cally J. Harper, the lead researcher on this new study. She found they’re active, engorging with blood and changing their orientation to serve as little nectar-scoops.

“When we get cold, the hair on our arms sticks straight up–it’s sort of like that, except that hair erection is powered by muscle, and in this case it’s powered by blood vessels,” Harper told Popular Science.

Another analogy: The bat tongues work like a mammal penis, engorging with blood to become stiff. Only much, much faster.

Harper used a Phantom v10 high-speed camera to film the bats feeding at 500 frames per second. Slowed down, the video clearly shows the tongue fibers–they’re called papillae–stretching out perpendicular to the rest of the muscle. It happens whether or not the bats actually stick their tongues in the nectar, which shows it’s not a passive response to surface tension. This is a hydraulic process–the same process that makes a starfish leg move, and the same process that makes the penis erect in mammals.

“When we were first thinking about this, we were like, ‘there’s no way that these tongues could be hydraulic.’ Most structures that are hydraulic tend to be slow,” Harper said. “The limbs in starfish, the penis erection mechanism in mammals, is really slow, but this happened in 40 milliseconds.”

She and her colleagues at Brown University tested it on tongues excised from dead bats. They injected the tongues with saline as a proxy for blood, and found as the tongue flicks out, it grows thinner as it elongates. As those muscles contract and increase the tongue’s length, they squeeze blood (or saline) into the tips of the papillae: A hydraulic process. “It’s a two-for-one,” Harper explains.

Plenty of other mammals use powerful tongues to force liquid into their mouths–high-speed video of dogs and cats show their curled tongues forcing columns of liquid upward. But when our pets drink, lots of liquid falls back into the bowl (or onto the floor). Not so for the bats, Harper said. Nectar droplets are caught among the papillae, and much more liquid gets into the bats’ mouths. This is an evolutionary advantage that can explain why such a complex structure would exist in only a couple species. The Pallas bat’s closest relative also has the tongue hairs, she added.

Hummingbirds also have unique tongue structures to help them obtain the maximum amount of nectar possible. It stands to reason that nectar-feeding bats, which have a similar metabolism, would also have some tongue tricks.

Harper–who defends her graduate thesis tomorrow–was interested in how mammal tongues work during feeding, and decided to focus on the bats because of the unusual hairs. But now she wants to turn the finding into potential new medical devices. A device that can hydraulically change its shape and structure could be useful for a whole host of surgical procedures, she explained.

“Technology modeled after these tongues could be especially useful for keeping blood vessels open during surgery, or keeping portions of the intestine open,” she said. “In some of the technology that’s out there for angioplasty and gastric surgery, the tools are made of these metal, rigid materials. I think it would be really great if we could make a medical tool that was soft and flexible, and could possibly minimize damage to blood vessels.”

Harper’s paper is published this week in the Proceedings of the National Academy of Sciences.

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So the first thing to know about bats is that there are two different suborders, which vary in geographic location and behavior but most importantly, for our purposes, in cuteness. Microchiroptera is the kind of bat we’re most familiar with here in the States; these are the little, semi-ugly ones that use echolocation to hunt. Now, we love all bats, because they are exceptionally fascinating creatures, but we’re prepared to admit that microchiroptera is not the most attractive suborder out there.

Macrochiroptera, on the other hand, is adorable! This second suborder is also known as the “megabats,” or, less scarily, as the fruit bats. These include the real big guys, like the flying foxes, but not all megabats are big. This little guy here is the blossom bat, and it’s tiny–the smallest macrochiroptera in the world, small enough to fit comfortably in the palm of your hand.

The blossom bat is native to Australia, where it eats, as you might expect, nectar and pollen from flowers. It’s not unlike a hummingbird in some ways; it’s a very small pollinator, equipped with a long, sticky tongue to snatch up delicious sugary nectar. It’s also quite rare, as it’s particularly susceptible to the destruction of its natural habitat. This particular bat, a female named Blossom, was found as a baby “after a suspected cat attack,” and rehabilitated at the Bat Conservation and Rescue Center. After a successful recovery, it was released back into the wild.

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Many species of bats use echolocation to orient themselves and to hunt their insect prey, but they also rely on a pretty detailed memory to find their way around, a new study suggests. Their seemingly erratic flight patterns are not erratic after all–they’re following detailed internal maps. Let’s call it batnav.

Jonathan Barchi and colleagues at Brown University wanted to figure out how bats seemingly remember complex flight patterns that take them through obstacles, dense clouds of other bats, and to feeding grounds far away from their cave dwellings. They send and receive calls at superfast speeds, but they also fly pretty quickly, so they don’t have much time to orient themselves in a given location. Figuring they must be relying on prior knowledge of their surroundings, Barchi and fellow researchers set up a bat obstacle course and set some bats loose.

They worked with big brown bats, Eptesicus fuscus, a common species that live in caves and forage for insects. The team hung chains from the ceiling in a dark room, and embedded sensitive microphones in the walls to record the animals’ ultrasonic calls. Then they released bats from specific locations, and reconstructed their paths using the microphone data.

After a couple of days of flights, the bats figured out preferred paths through the obstacles, the researchers found. Each bat found its own way–some looped in tight figure eight patterns, while others made wide lasso-like shapes, each according to its own preference. Then the team moved the bats’ release spots, and found the bats would soon re-establish their preferred flight paths.

Bat Paths

To test how well they could recall these patterns, the team put the bats on a month-long hiatus. The bats remembered the room and followed the same paths.

“We postulate that the development of stable flight paths allows bats to depend on their accumulated internal representation of a space, as well as on moment-to-moment echolocation, and to navigate within the space as a whole,” the team writes in their new research paper.

These findings could have implications for the neural basis of spatial memory. Unlike rats, which can stop in unfamiliar surroundings and orient themselves, bats are constantly on the wing, moving away from any given location all of the time. Somehow their brains are able to keep up with their ever-changing surroundings, the Brown team says. Their paper appears in The Journal of Experimental Biology.

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A new 3-D printed robotic bat wing can emulate the flapping motion of a real bat, helping biologists simulate how the mammals fly and helping aerodynamics researchers study new flapping-wing aircraft. In the process of building and modifying the robotic wing, researchers at Brown University stumbled upon some structural fixes that provide insight into how bat bodies evolved for flight.

Bat wings are incredibly complex mechanisms, producing lift and thrust to help the flying mammals quickly chase their insect prey, fly long distances, and nimbly move through dense clouds of their compatriots. A bat’s wings span almost its entire body, supported by two arm bones and five finger-like digits covered in an elastic skin that can stretch up to 400 percent of its original size. Small aircraft based on bat designs could be efficient little flapping drones, but researchers would need to understand how bats work.

Studying real animals poses a bit of a challenge, however, explains Joseph Bahlman, a graduate student at Brown who led the project. “We can’t ask a bat to flap at a frequency of eight hertz then raise it to nine hertz so we can see what difference that makes,” Bahlman said. “They don’t really cooperate that way.”

Researchers build a “robatic” bat wing from Brown University on Vimeo.

Instead, Bahlman and his team printed plastic bat bones and stretched a silicone elastomer “wing membrane” over it. The bones are connected to cables, which serve as tendons, and these are activated by built-in servo motors. The team could put the wing in a wind tunnel and test a bunch of parameters, like wing flap-frequency, related energy requirements, lift and drag, and so on. It’s based on the wing of a lesser dog-faced fruit bat.

Flapping wing aircraft (and animals) generate lift by flapping down and by folding their wings back a bit; think of hunching your shoulders forward and back, or rotating your wrist. Some of the downstroke lift is wiped out by the drag created on the upstroke. To avoid this, birds and bats fold their wings in a bit on the upstroke. By using the robot, Bahlman and colleagues found that wing folding increases net lift by almost 50 percent–a useful insight into how flapping-wing flight works.

But this research might be even more interesting for its insights into bat biology. During wing tests, a groove joint on the wing’s “elbow” kept breaking, for instance. Bahlman eventually wrapped it in some steel cable to keep it intact, just like ligaments holding joints together in real animals. The team also realized that real bats have a large set of muscles right at the elbow joint, and this may have evolved to prevent the elbow from bending to a breaking point, according to the researchers.

Then in further tests, the membrane started ripping on its leading edge. Bahlman reinforced that, too, using elastic threads. According to a Brown news release, the fix ended up resembling the tendons and musculature that reinforce real bat wings.

This underscores the importance of those wing structures–and could help explain why bats are so badly harmed by a debilitating fungus called Geomyces destructans, which coats their faces and wings. The fungus causes a deadly disease known as white-nose syndrome, and one of its characteristic symptoms is a badly infected and damaged wing membrane, preventing the bats from flying.

The robotic bat wing will help answer further questions about bat flight especially after the team starts tweaking its composition, according to Brown. The researchers want to change some materials to study bone flexibility, weight and other characteristics. Meanwhile, their initial research appears in the journal Bioinspiration and Biomimetics.

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Though they can rapidly spread pathogens that afflict humans, bats somehow avoid getting sick from viruses like Ebola, SARS, and other deadly bugs. A new genetic analysis of two very different bat species shows how the animals avoid disease, and live exceptionally long lives. It may all be related to their ability to fly, researchers say.

This research comes from the “Bat Pack,” a team of scientists at the Australian Animal Health Laboratory, and the Beijing Genome Institute. The team sequenced the genomes of a huge fruit bat and a tiny insectivorous bat and found both were missing a gene segment that can cause extreme immune reactions to infection. In most mammals, the so-called “cytokine storm” that results from an invading virus is actually what kills, not the virus itself. This inflammatory response doesn’t happen in bats.

By understanding how bats suppress this response, researchers might be able to design new drugs to minimize inflammation in people, according to Chris Cowled, a post-doctoral researcher at the Australian Animal Health Laboratory. This could include anti-inflammatory drugs that take cues from bats to suppress cytokine response, or it could be genetic therapy that directly targets certain segments of DNA.

But bats are not immune to everything. Millions of North American bats have perished from a fungal infection known as white-nose syndrome, which rouses the animals from their winter slumbers and causes them to starve. This new study is especially intriguing in light of a different recent study in insect-eating North American bats, which shows they can suffer an acute immune response in the face of an invader. When bats are hibernating, their immune systems are suppressed, which makes them more susceptible to white-nose infection. When they wake up, their immune systems go into overdrive. This is called immune reconstitution inflammatory syndrome, or IRIS. This has only been observed once before–in AIDS patients.

What makes bat immune systems so adept at handling viruses, but so weak at handling fungi? Ongoing research should provide some answers. What’s more, understanding how bat and human immune systems compare could shed some light on human disease prevention, too.

Beyond their avoidance of viral infection, bats have evolved to resist aging-related illnesses and cancer, the researchers say. Compared to other animals their size, like rodents, bats live an extraordinarily long time–between 20 and 40 years, compared with two or three for a rat. The researchers believe all this has something to do with the animals’ ability to fly.

Flying requires intense physical activity and expends vast amounts of energy, which produces toxic free radicals that can cause tissue damage and cancer. To deal with this, both species evolved a surprisingly large amount of DNA repair genes, the authors found. They believe the heavy mutations helped the bats maximize their metabolism, which in turn allowed them to take flight. One specific gene, called P53, is involved in cancer and repair of damaged DNA.

“We’re proposing that the evolution of flight led to a sort of spill over effect, influencing not only the immune system, but also things like aging and cancer,” Cowled said in a statement.

The study examined two very distantly related bat species, the black flying fox of Australia (Pteropus alecto) and David’s Myotis of China (Myotis davidii). It appears in the year-end issue of Science.

David’s Myotis

CSIRO

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The millions of bats succumbing to a deadly fungal infection across the country will leave massive ecological holes in their wake–prime predators of insects are disappearing, for one, and cave flora and fauna that depend on bats could be in danger of collapsing. But research on the animals’ immune responses could have one silver lining: helping AIDS patients.

Biologists think white nose syndrome kills bats in a couple of ways–first, by covering their faces and wings in a powdery white fungus that makes them itchy, causing them to wake up from hibernation and burn their precious fat reserves. Second, it damages the animals’ sensitive wing membranes, which causes system-wide injury that is still not totally understood. That also hurts their ability to fly.

Bat immune systems try to fight off the fungus, and apparently the system goes into overdrive when hibernating bats wake up. This is called immune reconstitution inflammatory syndrome, or IRIS. It has never been seen before in the wild, and has only been observed once–in AIDS patients.

In people with AIDS, the immune system goes into overdrive after antiretroviral drugs suppress HIV infection and restore a person’s health. The immune system then tries to fight off any other underlying infection. In bats, this happens after the animals wake from their winter torpor. During that stage, the immune system is suppressed, which allows the Geomyces destructans fungus to colonize the bats’ skin in the first place. In both cases, the awakened immune system goes out of control and attacks healthy tissue as well as infected cells.

Carol Meteyer, a scientist with the U.S. Geological Survey, noticed the phenomenon while studying sick bats in Wisconsin. “It’s cellular suicide. [The immune system] comes out in a huge wave, going out to those areas of infection and kills everything,” she told the Washington Post. Now she and colleagues at the National Institutes of Health aim to study the similarity between bat and human immune systems, potentially learning how IRIS works in people.

The hypothesis about bat IRIS was published last month in the journal Virulence.

[U.S. Geological Survey, Washington Post]

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Except when they freak us out by getting into the attic, this time of year is arguably the only time anyone notices bats — they adorn T-shirts, cupcakes and front doors, symbolizing all the creepiness and darkness of Halloween. Of all the holiday’s motifs, bats are arguably the least understood and the most maligned. But they are in fact cuddly, clean and sociable creatures, and you should not be afraid of them! Here’s why.

Joy O’Keefe, director of the Indiana State University Bat Center, says she understands the Halloween connection — bats are spooky because they’re out at night, go into damp, dark places and make no noise.

“People fear what we don’t understand, and with bats nocturnal, and tending to be small, they’re cryptic,” she said. “Even us bat biologists don’t know a heck of a lot about them. It only takes a few wrong turns to perpetuate myths and fears about bats.”

It’s actually hard to pinpoint a specific reason why bats became so entwined with this holiday. Many of the bat experts I talked to mentioned the Dracula movies of the 1950s, which solidified the bat-vampire myth. O’Keefe notes that you see them a lot around Halloween, because they’re swarming now and mustering into caves for the winter. Other theories suggest they’ve been Halloween beasts since the beginning. As Celts celebrated their harvest festival Samhain, which evolved into Halloween, they lit bonfires, which attracted insects — which attracted bats. But this isn’t clear.

Mark Mirabello, a history professor at Shawnee State University in Ohio, said nocturnal animals in general may have evoked death because night time is the realm of the dead. “The dead are weakened by light, and daylight in general — that may be why a bat is often associated with death, a ‘night stalker,'” he said.

Steve Siporin, a history professor and folklorist at Utah State University, said Samhain was a new year’s celebration, marking the beginning of winter.

Bats Are Small

“All the symbols have to do with death, because it’s the death of summer; harvest is coming to an end. That’s the origin of symbols like skeletons, and ghosts, and all that,” Siporin said. But bats? He said he’d never thought about it before I asked, but it turns out they fit this theme perfectly.

“One of the main themes of Halloween is liminality — the in-between-ness. It’s between one state and another state; between growth and death; between fall and winter, the beginning of the new year. There are all sorts of symbols of that in-between-ness,” he said. “It occurred to me that one of the things about a bat is it has a liminal kind of quality — it’s a liminal creature. It’s a mammal, and mammals generally belong on the ground, they don’t fly. It takes part in two different worlds.”

He also noted that Halloween is unique because it incorporates nature. Pumpkins, obviously, but also squash, corn stalks and other plants feature prominently this season — so it makes sense that bats would as well.

“Halloween crosses a lot of boundaries, and I keep coming back to the bat because it crosses boundaries, too,” he said.
“When we compare them to, say, rodents, there’s not quite as many species, but in terms of diversity of diet and function and form, we see a greater diversity in bats,” she said. “They’re the only true flying mammal, and nocturnal, which of course makes them very difficult to study.”

Bats are the only flying mammals.

There are about 1,200 species in all, which is almost a fourth of the total number of mammals, said O’Keefe.

Mary Jean “Corky” Quirk, an educator with NorCal Bats in Sacramento, has three live bats she brings to presentations and schools. The animals were injured and couldn’t be released, so now they serve as wildlife ambassadors, she said. Schoolkids and adults are almost always enchanted by them once they get a look.

“One thing that amazes people the most is how very small bats in the U.S. are,” she said. “When they are able to actually see the bats more closely, they can begin to see what their faces look like. They’re much more dog-like than rodent-like.”

Also, they are constant and obssessive groomers, so they’re very clean (although their caves are, well, not).

Shou Character And Bats

Bats protect and pollinate crops, from walnuts to tequila.

A colony of 1,000 Mexican freetailed bats can eat the equivalent of two full grocery bags (the brown paper kind) of insects every night, according to an estimate from researchers at Sacramento State University. If bats didn’t eat them, the insects would be free to eat crops with abandon, increasing pesticide use and destroying yields, said Rachael Freeman Long, a University of California Cooperative Extension adviser. Almost all North American bats are insectivores, so this is true throughout the U.S.

In the southwest and in Mexico, nectar-eating bats are the primary pollinators of several cactus and agave, which is used to make tequila.

Other cultures are not so anti-bat. In China, for instance, they’re powerful good luck symbols. The word for “bat” in Chinese (fú 蝠) sounds like the word for good fortune or happiness.

Bats are in trouble.

More than 5.5 million bats have died from a fungal infection known as white-nose syndrome, and their populations could take decades to recover, if they do at all. Bats have extraordinarily long lifespans, O’Keefe notes, sometimes living 40 years. They give birth to one pup per year, so rebuilding bat colonies will take a long time.

Whatever the origins of their Halloween story, it’s a good excuse to celebrate bats. Happy Halloween!
^._.

Not Scary

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Echolocation is a bat’s prime method of finding food and orienting itself, but it also helps the animals find and keep their mates, according to a new study. Bat calls contain detailed information an individual’s identity, which helps male bats avoid rivals and helps females find their partners.

Researchers in Germany studied the greater sac-winged bat (Saccopteryx bilineata) and discovered their calls encoded information like gender, age, group affiliation and individual identity. Much more than sonar for hunting, the ultrasonic calls help bats woo each other. The team, led by Mirjam Knörnschild, played female bat calls to male bats, the males responded with “courtship vocalizations,” while male calls played to males elicited aggressive replies. The new research appears in the Proceedings of the Royal Society B.

ABC Science

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Bats are great at hunting down prey via echolocation, in which their ultrasonic chirps bounce off anything in the air. Specialized ear designs and other features detect the returning sounds, helping the bats determine the location of a moving target. But what about when the target is still?

Bats have been observed seeking out and catching inert insects hiding amid clutter, and finally scientists think they’ve figured out how the animals do it. The flapping motion of a bat moves the air sufficiently to ruffle the wings of their insect prey, and this trifling perturbation can be detected. Understanding the way bats do this could help improve biomimetic sensors, according to Roman Kuc, professor of electrical engineering at Yale University, and his colleague/son Victor Kuc.

The father-son team filmed a common big-eared bat, Micronycteris microtis, with a high-speed camera. The bat hovered over a completely still dragonfly sitting on a leaf, and was able to detect it and pick it up. Watching the playback in slow motion, the Kucs noticed the dragonfly’s wings move ever so slightly in the air current caused by the flapping bat. The dragonfly wings moved in sync with the bat wings. The Kucs then made a model of the induced wing movements and how they affected the returning echoes, according to Yale’s School of Engineering and Applied Science.

To do it, they took a real dragonfly, plastic leaves and a robotic sonar system to generate sound pulses. They used an airbrush to puff air at the dragonfly, simulating the beating bat wings. The resulting echo waveforms gave it away: The leaf didn’t really ruffle, but the dragonfly wings did. The Kucs say that bats can figure out the difference, and use it to detect the location of prey that is otherwise silent and totally still.

The study is published in the Journal of the Acoustical Society of America.

Yale News

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CLARKSVILLE, Tenn. — Up a crunchy gravel road not far from the Kentucky line, buried in a hillside a few steps from a huge limestone cave network, an audacious experiment is about to take place. The first-ever artificial cave for hibernating bats, built specifically to protect the animals from a debilitating fungal disease, is almost ready to welcome its first residents.

At this point in the season, the bats of Bellamy Cave are still in their summer roosting colony. When temperatures drop and fall takes over, they’ll move to a midseason staging area to acclimate their bodies, and by mid-October — depending on the weather — they’ll fly into their winter cave to sleep the cold away. The Nature Conservancy hopes they’ll pick the customized 78-foot-long, 11-foot-high concrete cave instead.

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Click to launch the photo gallery_

Sick of watching helplessly as hundreds of thousands of bats die from a disease known as white nose syndrome, the Conservancy’s Tennessee chapter decided to build the new cave as a sanitary hibernaculum. Made of modified road culverts and adorned with metalwork from which bats can suspend, it can be disinfected every spring. The aim is to reduce the amount of Geomyces destructans spores that can attack the bats’ wings and faces, blanketing their noses in a snowy fuzz of fungus.

“It’s too depressing to count sick bats and dead bats,” explained Gina Hancock, Tennessee director for the Conservancy. “There’s something about seeing them outside, in the winter, and dead on the ground. There’s just something heartbreaking about it.”

Tennessee has more documented caves than any other state, and it’s home to hundreds of thousands of bats, 16 species in all. About 265,000 of them, mostly gray bats, live in the Bellamy Cave network, where white nose syndrome was first documented this March. The artificial cave can hold at least 160,000 of them.

The artificial cave is outside of Clarksville, Tenn., about 20 miles south as the crow flies from the sprawling complex of Fort Campbell, Ky. The only neighbors are a few small homes with chickens in their front yards. When I pulled up, there was not a person in sight nor a sound to be heard; it was like some Stephen King plot where everyone slips through a time rip without warning. I side-stepped down the steep hill toward the woods, figuring I would stumble upon the cave, and finally I head the dim echo of a human voice. The Tennessee drawl of Cory Holliday floated up the cave entrance and into the air.

When you go into a cave and there’s no bats, it’s pretty depressing. It’s just a miserable day. It’s very motivational to do something like this.

Holliday, director of the Cave & Karst Program for The Nature Conservancy in Tennessee, stood in the bowels of the artificial cave — it doesn’t have a name yet — and pointed out its bat-friendly features. Curled fan belts and netting attached to the ceiling will provide a comfortable hibernating spot for gray bats and Indiana bats, and crevices in the wall will welcome Eastern small-footed bats. A rainwater pipe will bring in moisture to maintain the cave’s humidity levels and provide drinking water, and an air chimney will provide ventilation. It will also have surveillance cameras so humans can keep an eye on the bats without disturbing them. Two 1.5-ton air conditioning units will run for the next few weeks to drop the cave’s temperature to the required range, between 41 and 50°F, and Holliday is still working on getting the humidity levels right.

It’s built from huge concrete culvert pieces, the same structures that provide waterways under roads and highways. The Nature Conservancy designers added extra texture on the ceiling to give bats a foothold. The 17- to 20-ton sections fit together like Tinker Toys — a modular design that kept the price low and could be easily replicated elsewhere, if it works.

“We’ve got to try,” Holliday said. “When you go into a cave and there’s no bats, it’s pretty depressing. It’s just a miserable day. It’s very motivational to do something like this.”

Though the cave was simple to construct — it was built in a week in late August for $300,000 — engineering it to the bats’ specifications was a challenge, Holliday explained. Natural hibernacula contain a cold air trap, which keeps the bats’ body temperatures low enough to remain in torpor. To create a cold air trap, the ceiling has to be lower than any entrance, so cold air will sink into the cave and remain there. It has to provide air flow through two entrances, which must be at different levels, and it has to be underground. The artificial cave is buried beneath four feet of dirt, Holliday said.

Why go to all this trouble and not just sanitize the real cave instead? That would collapse the entire cave ecosystem, explained Sally Palmer, director of science for the Tennesee Conservancy. Spraying caves with fungicide to kill G. destructans would kill beneficial fungi, too, and then fungus-eating creatures would die, and so on — insects, amphibians and even fish make their homes in caves. “It would wipe out the food web,” Palmer said.

The artificial cave won’t prevent the white nose fungus from entering, but if wildlife managers can clean it every spring, the cave will be safe when the bats come back in the fall. If an infected bat can make it through the winter, it will heal throughout the summer — so keeping the caves’ spore count lower would help.

Artificial Bat Cave

Half of Tennessee’s bats are susceptible to white nose syndrome, which has decimated the animals throughout the Northeast and Atlantic regions since it was discovered in 2006. About 5.5 million bats have succumbed so far in the U.S., according to the best estimates from state and federal wildlife officials. The G. destructans fungus damages the bats’ wings and causes them to wake up when they should be in torpor. This burns their fat reserves too early, and the animals either starve to death or try to leave their caves in the dead of winter in search of food, instead dying of exposure.

The disease is turning up farther west every spring, and there’s not much people can do about it other than count bats to keep tabs on them, protect cave entrances and hope for the best. The artificial cave could be a lifesaver, and wildlife officials from several state and federal agencies are watching closely to see how well it works.

“I think people were waiting for the first person to stick their neck out,” Hancock said. “We’re less risk-averse than our public partners.”

Even after all this effort, no one is sure if the bats will come in. There’s good evidence to suggest they will — bats are always seeking out different habitats — but it’s not a sure thing. If they don’t, The Nature Conservancy can still use the cave as a field laboratory, Holliday said. They might bring some bats into the cave for testing, or they might try out new fungicides.

If it does work, the artificial cave could be a model for other projects around the country, according to Hancock. She is even interested in working with the military to use abandoned bunkers, or to use artificial caves as captive breeding sites.

To entice them, The Nature Conservancy is installing ultrasonic speakers that will play bat calls common this time of year.

“Then at least they’ll know it’s here,” Palmer said. “It’s a crazy thing to go ahead and try — but let’s try it.”

Inside the Artificial Bat Cave

Gray Bats in Tennessee

Cave Under Construction

Bat Entrance

Human Entrance

Artificial Bat Habitat

Cory Holliday

An Entrance to Bellamy Cave

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The hundreds of millions of bats in the U.S. are in serious trouble, threatened by such hazards as wind turbines and a fungal infection called white-nose syndrome, all while facing the uncertainty of a changing climate. Most bats hide in caves during the day and live in the air at night, making them notoriously difficult to study. But if scientists are going to help them, they need to be able to track them.

To that end, biologists Winifred Frick of the University of California at Santa Cruz and Tom Kunz of Boston University have teamed up with some unexpected allies: weather researchers Phillip Chilson, an atmospheric physicist at the University of Oklahoma, and radar scientist Ken Howard of the U.S. National Severe Storms Laboratory.

The U.S. National Weather Service’s 156 Nexrad Doppler radar stations gather a tremendous amount of data. They scan the country in five- to 10-minute intervals, 24 hours a day, from 0.5 degrees above the horizon to 19.5 degrees. And in doing so, they detect much more than weather. Anything in the air bounces a signal back—insects, birds, wind turbines, low-flying planes, forest-fire smoke, falling meteors, debris from NASA disasters, and bats. Radar scientists call the signal from flying animals bioclutter. “From a meteorological standpoint, it’s noise,” Howard says. “It contaminates all our algorithms. It misleads people. We have examples that look like severe storms, but it’s actually bats coming out of the ground.”

Raw Signal

The weather-radar images shown on TV broadcasts have mostly been scrubbed of such clutter. But unscrubbed maps are far more complex. Clear, cloudless nights are filled with flocks of animals on the wing, which appear on radar maps as a thick cloud of fuzzy green dots, similar to raindrops. If a cloud of bat-size objects appears at dusk at the location of a known bat cave, they’re probably bats, which means that the Weather Service’s 20-year-old, 1.2-petabyte raw radar archive is also an archive of two decades of bats in flight.

The Nexrad archive has already generated several new observations and even a new field of science: aeroecology, a term Kunz coined last year. Frick has noticed that in a dry year (when insects are less abundant), Brazilian free-tailed bats in a certain Texas cave emerged from their daytime slumber earlier in the evening to get a head start on mealtime. During a wet year, they slept in. Using the archive, Frick also spotted insects pooled along a storm front, where winds shepherded them together. On several nights, the bats gathered to feed on the wind-formed buffet line—clear evidence that weather influences foraging activities. She says she wants to study the entire two-decade archive, including looking at whether the free-tailed bats are starting to spend the winter in Texas rather than heading farther south, which would be an indication that a warming climate is changing migration patterns.

Eventually, the scientists aim to use the data to count population numbers at each cave. The algorithms that determine the identity of objects in the sky are not yet nuanced enough for a census. But they could be improved, helping both meteorologists and biologists better determine, for example, what’s a cloud, what’s a bat-cloud and what’s an insect-cloud. (Bioclutter still sometimes contaminates weather-only maps, looking like a storm.)

Weather Map

Radar scientists are working to make the archive more useful for researchers. One of their goals is to produce animal-only maps and animal counts, much as they produce weather maps and rainfall counts today. In order to accurately screen for various life-forms, though, the scientists need to know more about how individual animals appear on radar. Last summer, Chilson and Frick scanned live bat swarms in west Texas with a mobile radar device (designed for tornado chasing) while also using infrared cameras to identify individuals. Chilson even put a dead bat in an anechoic chamber to precisely map its radar signature.

Howard says that the animal-tracking project could also help biologists studying insects and birds, particularly those observing nocturnal airborne behavior. The aerosphere is a habitat just like the land or the ocean, “but we never stop to look at it,” he says. “Most of these things happen at night. There’s a whole richness of life that’s going on that is not visible, unless you are a biologist with night-vision glasses—or if you are using radars.”

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The only mammals that can fly are also the only mammals with a larynx that flexes at ludicrous speed, a new study shows. As bats flip and whirl toward their prey, they chirp at an accelerating rate, increasing their echolocating calls to 160-190 chirps per second. This is possible because their laryngeal muscles can contract up to 200 times per second, researchers say.

Bats start out with shorter-rate chirps, increasing their frequency as they approach their quarry and culminating in a superfast pulse called the terminal buzz. Watch the video below to see what this sounds like. Coen Elemans and John Ratcliffe at the University of Southern Denmark set out to study how bats produce this buzz. They also wanted to determine whether the upper buzz limit is a function of how quickly the bats can hear the return signals that bounce off their prey, or whether it’s because of the bats’ own call-producing abilities.

They set up a chamber with 12 microphones and recorded the activities of five different free-flying Daubenton’s bats, little bats found in woodland areas from Britain to Japan. The bats hunted mealworms that were suspended in the chamber. The animals’ chirp rate was so rapid that the researchers knew they couldn’t be using normal skeletal muscle.

They attached the bats’ vocal muscles to a motor and a force monitor, and stimulated the muscles to flex. The researchers monitored how long it took a muscle to twitch, and determined the muscles were able to contract and relax at frequencies up to 180 Hz and, in one case, up to 200 Hz.

They also noticed that echoes from individual calls ended before the start of the next call, so the bats don’t confuse themselves. But a bat could theoretically produce calls at a greater frequency than 200 Hz — up to 400 Hz before echo interference would become a problem. The reason they don’t? The superfast muscles are only so fast.

Andrew Mead, a biology graduate student at the University of Pennsylvania’s School of Arts and Science, said the muscle performance could be equated to a car engine: “It can be tuned to be efficient, or tuned to be powerful depending on what you want it to do.”

Bats trade off some force to achieve the rapid oscillations, he said in a statement. “In a way it’s like an engine that’s been tuned for extremely high RPM.”

These laryngeal muscles contract at a rate 20 times that of the fastest human eye muscles, and about 100 times faster than typical skeletal muscles, the researchers say.

Bat Aerobatics

Previously, scientists thought these ridiculously quick muscle contractions were only found in the sound-producing organs of rattlesnakes and some types of fish. In 2008, Elemans located them in songbirds, too, and now he’s found them in the first mammal. It suggests that these special muscles are more common than previously thought.

The research is published in today’s issue of the journal Science.

Science

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A week before last December’s massive floods in Queensland, Australia, volunteers from the Australian Bat Clinic and Wildlife Trauma Centre rescued 150 orphaned grey-headed flying foxes, these five among them.

Clinic co-founder Trish Wimberley says the mothers may have left their young because they sensed the coming flood or were suffering from starvation. Preserving these endangered bat populations is important, says Winifred Frick, a National Science Foundation bioinformatics postdoctoral fellow, because bats perform “ecosystem services” such as pollinating plants and eating insects that would otherwise consume crops.

Generally, the clinic releases the animals back into the wild after 16 weeks of feeding and medical care, but because they were severely undernourished when found, these bats will require extra care before being brought back home.

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Bat Ears

Bats — you know we love ’em — have a remarkable ability to turn, swirl and dive on a dime while in mid-flight, dodging obstacles and grabbing food from the air. Engineers would like to give robots and autonomous vehicles this ability, and they’re turning to bat ears for inspiration.

Most bats use echolocation to find prey and to navigate, and biologists are learning that their handwings have a lot to do with their precise movements. But there is also growing evidence that bats can store and quickly compute sensory information, not unlike a bloodhound capturing scents in its wrinkled neck. Bat ears in particular are designed to capture sounds and vibrations in the air. The geometry of these features could be useful for autonomous flight systems, according to Rolf Mueller, assistant professor of mechanical engineering at Virginia Tech.

Most autonomous systems have lasers, sonar, or video cameras that can deliver vast streams of two- and three-dimensional data, helping the robot or aircraft sense its position and the obstacles it must face. But sometimes there’s just too much information, which can overwhelm the systems’ necessarily small on-board computers. Bats can compute all these inputs very quickly, however. Their ear baffles, ranging from tiny to enormous, may help them do this, with ridges, grooves and flaps that help them perceive their environments. Some bats also have “noseleaves,” small flaps of skin growing from their noses, which are thought to be sensitive to vibrations in the air.

The ultrasonic waves that bats emit are bounced off these ridges and flaps and diffracted in a certain pattern, depending on the frequency of the sound wave and the shape of the ridge or flap in question. The bat is able to filter these inputs at the speed of sound, making split-second decisions about which way to turn or dive, Mueller explains in a Virginia Tech news story.

Mueller is studying bats’ use of “sidelobes,” secondary ear structures that point away from the most sensitive auditory centers. These structures apparently heighten their sense of hearing. In most radar systems, sidelobes are considered a noise-creating nuisance, but Mueller’s bat research suggests they might be useful. He says understanding bat physiology could lead to better biomimicry, leading to customizable sensing systems.

Virginia Tech Research Magazine

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Bat Con 2010 could have been a decidedly depressing science meeting, with days full of papers discussing bat deaths from white-nose syndrome, wind turbines and killings by superstitious people. But not everything was doom-and-gloom.

The same researchers trying to protect bats from extinction are also working with the Air Force and Navy to design bat-inspired drones; they are using 3D thermal imaging to understand how bats fly in tight-knit groups; and they’re using sophisticated weather radar to track bats, birds and insects as they migrate across the continent. Bat research is fruitful for many fields.

In September, researchers at Boston University, the University of Maryland and other institutions won a five-year, $7.5 million grant from the Office of Naval Research for a project called AIRFOILS (Animal Inspired Flight with Outer and Inner Loop Strategies), designed to develop unmanned aircraft inspired by the flight mechanics of bats, birds and insects. The military has already invested in hummingbird-inspired drones, and others have looked at bat-inspired micro-aerial vehicles, but this time the funding reaches across several disciplines.

Tom Kunz, a bat biologist at BU, is using LIDAR and 3D thermal imaging to monitor bats and recreate their flight mechanics. His Airfoils project is intended to explain how bats fly in cluttered environments. “It allows me to do the biology I’ve always wanted to do, but it also inspires engineers to create new aircraft,” he said.

When bats emerge from caves to forage at night, they fly in a dense column, snaking through the air for several miles until breaking apart to feed. Kunz and a former postdoc, Nickolay Hristov, are reconstructing bat flight patterns to understand how and why this happens. They’ve learned that bats fly at an average speed of 20 mph, and their behavior is actually not as complex as it looks. Think of cars driving on a highway: “If you are sitting in the middle, it looks intimidating. But when you are in the traffic, it becomes an individual balancing act,” Hristov said.

Understanding this balancing act could help engineers design better autonomous control systems for unmanned aircraft.

The Pentagon would also like to know more about how bats are able to change speed or shift directions on a dime. To that end, researchers at Brown University studying bat handwings have learned bats’ skin is almost as important for flight control as their joints. Every species the team examined had at least one joint that lacked muscles on one side — but the bats are still able to flex them as if they had muscles. Joseph Bahlman, a doctoral student, said bat wing skin is crucial for transferring force, like a muscle normally would, and that this happened because heavy muscle loss provided an evolutionary advantage. Better understanding of how this works could inform development of robobat drones.

Military technology is coming full circle and helping bats, too. Conservationists in several states are using missile-tracking programs to track the heat signatures of bats, and researchers are checking Doppler radar images for bat migrations and cave emergences. Winifred Frick, a postdoctoral researcher at the University of California-Santa Cruz, is using the National Weather Service’s 159 NEXRAD Doppler radars to monitor bat movement.

Bat Doppler

Weather forecasters already have algorithms that can estimate the number of raindrops inside a rain cloud, so Frick hopes they can be tweaked to estimate the number of bats in a bat cloud. To do this, Phillip Chilson, a meteorologist at the University of Oklahoma, is putting bats in special wind tunnel chambers and measuring their backscatter cross-sections to estimate density.

This will improve bat population counts and help scientists measure their migration patterns, which will improve conservation plans for proposed wind farms, among other topics. Doppler radar can also pick up insects and other creatures living in the aerosphere, the layer of the atmosphere closest to the ground. Two years ago, Kunz proposed a new field called aeroecology, which studies the biological and mechanical systems that affect the aerosphere.

He has a National Science Foundation grant to expand this research and hopes to present a paper on it at the American Association for the Advancement of Science annual meeting in February. He will discuss how atmospheric scientists, biologists and engineers can work together to understand and protect creatures that use the aerosphere — proving, once more, that bat studies are important for much more than the bats themselves.

Dave Dalton/Wildlife Engineering

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DENVER — Bad news for bats: Mother Nature is not the only thing wiping them out. Anthropogenic climate change and renewable energy technology are also wreaking havoc on bat populations throughout North America. Biologists are looking for ways to protect bats not only from a devastating fungus, but from wind turbines and global warming.

Warmer temperatures and drought brought on by climate change could disrupt migration and mating patterns, researchers said this week at the North American Society for Bat Research annual conference. Rick Adams, a biology professor from the University of Northern Colorado, published a paper in August that showed bat reproduction declines when conditions mimic climate change. Examining 15 years of data from bats along Colorado’s Front Range, he found as temperatures rise, the proportion of reproductive female bats goes down. A colleague at UNC, Mark Hayes, hypothesized that the same will hold for drier conditions.

A warmer climate could hold some unexpected benefits for white-nose syndrome — researchers think bats that are commonly found in the southeastern United States, like the tricolor bat, could move farther north and replace the little brown bat, which is being decimated by white-nose. What’s more, the fungus grows best in cold conditions, so if mid-Atlantic and northern caves get warmer because of climate change, it could spread more slowly or even die out. But Hayes’ study found warming climates will ultimately kill off bats, too.

Ironically, one method to ameliorate climate change could make matters even worse for bats. Wind turbines, favored for their carbon dioxide-free power generation, are deadly for bats, especially tree-roosting species that migrate over long distances. One study from the Blue Sky Green Field Energy Center in Wisconsin found for every megawatt of wind energy generated, 22 bats die every year.

Unlike birds, which often perish at wind farms when they collide with the turbines, bats die in blade vortices. Rotating turbine blades create negative pressure pockets, and when the bats fly through them, their lungs explode.

“Some wind sites are killing hundreds to thousands of bats in a single fall migration season,” said Paul Cryan, a research biologist with the US Geological Survey. One wind farm in New York is estimated to kill more hoary bats every year than have ever been collected for scientific studies, he said.

Some scientists have proposed turning off wind turbines during peak migration periods, and others have proposed unconventional solutions like painting turbines darker colors to baffle the bats. But a new study to be published Monday in the journal Frontiers in Ecology and the Environment says there could be a simple fix: Reducing the cut-in speed, or the wind speed at which wind turbines switch on.

Most wind turbines in the US are programmed to begin rotating and producing power once wind speed has reached about 8 to 9 mph, according to the Ecological Society of America. Ed Arnett, a biologist with Bat Conservation International, says raising that speed to 11 mph can reduce bat fatalities from 43 to percent up to 93 percent. Even better, the annual energy loss was less than 1 percent.

Wind turbines will still kill bats — during two summers of study at a Pennsylvania wind farm, Arnett sometimes found fresh carcasses even when turbines turned on less frequently. But when they turn on at higher wind speeds, they will not kill as many. For the most part, bats don’t fly when it’s too windy.

“Rarely do you see such a win-win result in a study,” Arnett said. “There is a simple, relatively cost-effective solution here that could save thousands of bats. This is good news for conservation and for wind energy development.”

Researchers still don’t know why bats are attracted to wind turbines, however. Some hypothesize that they mistake them for trees, which explains why 75 percent of bat deaths are among tree-roosting species. Most bat deaths at wind turbines happen in early fall, which is mating season; the “tall tree hypothesis” suggests that bats think wind turbine towers are attractive mating sites. “Tall things are mistaken for singles bars,” said Craig Willis, a biologist at the University of Manitoba.

To study this, Willis and Cryan examined the mating readiness of bats killed by wind turbines in New York, Manitoba and Alberta, and found most male bats were ready to reproduce. The researchers couldn’t find evidence that the bats were copulating at the wind farm, but their genitalia indicated it was the right time of year, Cryan said.

“It’s easy to come up with these hypotheses, but this is one I hope we can disprove,” he said. “If you are selectively causing the death of the reproductive class, you are in trouble from a conservation standpoint.”

Bats are a keystone species — disruptions to their reproductive patterns and populations will have cascading effects throughout entire ecosystems. Protecting them from wind turbines is just one more thing for conservationists to worry about.

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DENVER — Gerald Carter walked over to Dave Dalton’s table and paused, listening to a discussion about infrared light. He set down his backpack full of video and audio equipment and smiled. “I love this lamp. I left it running for three months,” he said, eyeing a round black object. He has three hard drives’ worth of vampire bat videos, all illuminated by the special infrared lamp Dalton sells. It’s a fondness only bat researchers could appreciate.

Any wildlife biologist will tell you it’s difficult to study wild, free-ranging animals in their natural habitats. You have to find them first, then catch them, examine them, attach radio transmitters or tags to them, and let them go. Now try that when your subject is silent, nocturnal and all but invisible.

Advanced technology is intrinsic in the study of bats — for the most part, we can neither see nor hear them, so biologists use a suite of special microphones, cameras and telemetry equipment to uncover their secrets.

“You need special equipment to get into their world. To get even the most basic information, you need really advanced technology,” said Carter, a PhD candidate at the University of Maryland.

Carter studies cooperation and social behavior among vampire bats, and he uses equipment that costs nearly as much as tuition. One of his ultrasonic microphones is worth $10,000 — he’s borrowing it so he didn’t have to buy it.

“If I was studying birds, I could just go to Radio Shack and get a digital recorder,” he said.

Vendors like Dalton offer the latest infrared lights and cameras; high-speed video; ultrasonic microphones; and special processing software that allows researchers to better see and hear bats. At the North American Society for Bat Research annual conference this week, biologists are buying technology like tiny radio transmitters — the smallest one on the market weighs just 0.006 ounces — and learning how to shoot and edit video to improve their research and communicate with the public. Carter has even used high-speed cameras to watch vampire bats running on a treadmill. Software called Sonobat can capture bat calls, slow them down and turn them into digital images, which biologists can use to tell different species apart.

Even the Army is involved, at least tangentially — technology initially developed to track missiles is now being used to track bats. The Army Corps of Engineers worked with the US Fish & Wildlife Service to set up thermal infrared cameras that can track the heat signatures of individual bats, said Tony Elliott, a staff scientist with the Missouri Department of Conservation. The cameras can help researchers monitor bats flying in and out of caves.

All this advanced tech will help bat biologists in the battle against white-nose syndrome, which is killing hundreds of thousands of bats throughout North America.

Passive acoustic monitoring equipment can inform biologists when bats behave abnormally, such as using echolocation in the middle of the day or during the height of winter. Michael Schirmacher, a biologist with Bat Conservation International, said most bat researchers have special Anabat II acoustic detectors sitting in storage over the winter, but they can easily be used to monitor white-nose in the cold months. Last winter, he placed detectors in infected caves throughout Pennsylvania and was able to verify abnormal activity without ever setting foot in a hibernacula. That’s important because many biologists believe humans can carry white-nose fungus on their clothing or equipment, unwittingly infecting bat caves.

Researchers also use lasers to monitor cave emergences and infrared cameras to watch bats grooming themselves — until, as grad student Sarah Brownlee found out, a wayward rabbit chews through the cables.

There are some low-tech solutions, too. Thomas Kunz, a biologist at Boston University, advocates using scrap wood to build roost modules, basically little nests where lactating bats can hang out. Bats cluster together to keep warm, and when they’re dying by the hundreds of thousands, maternity colonies will have less ambient heat to help the few survivors. Artificial roost crevices can help, Kunz said.

Bat biologists are frequently asked how they can help save bats from white-nose, and Kunz said bat houses and roost modules are one easy answer. Then again, electrical engineers with a penchant for designing cameras could pitch in, too.

Al Hicks, a retired wildlife biologist from New York, said bats need all the help they can get: “It’s our obligation to get a handle on this. if you can contribute in any way, we need you. It’s going to take quite an imagination to get a handle on this.”

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DENVER — What’s a crisis if not an opportunity? Scores of graduate students reporting new research at a bat conference this week shows the two are tightly bound.

Students are working on the front lines of one of conservation biology’s biggest challenges: The widespread death of bats from white-nose syndrome. The fast-moving fungus, which is expected to infiltrate much of the midwest and west this winter, is causing equally brisk priority shifts in academic institutions across the continent.

Students who were initially interested in topics like wind turbines and bat social behavior are shifting their focus to white-nose research. Even seemingly unrelated topics, like new methods for examining bat guano, is at least partly colored by white-nose and its impacts.

Money is one motivator, students and advisers say — private and public agencies are funneling hundreds of thousands of dollars into white-nose research, so biologists who don’t study it directly may have a harder time getting funding.

Alan Hicks, a retired wildlife biologist from New York, was the first field researcher to recognize white nose syndrome back in 2006. He’s been beating the drum ever since and practically begs graduate students to study the disease. He recently sent a former student, Kate Langwig, to work with another prominent bat researcher, Thomas Kunz of Boston University, with a promise: “I said, ‘I will haunt you to your dying days if you don’t try to solve this white-nose thing,'” he recalled.

But most young people don’t need the prodding — they say their love for bats and frustration about their plight are the biggest consideration. “I love bats — I don’t want to see them die,” said Sarah Brownlee, a master’s candidate at Bucknell University.

Brownlee’s interest in bats stemmed from undergraduate research on wind turbines, the other major bat killer. As an undergraduate at East Stroudsburg University in Pennsylvania, Brownlee knew she wanted to study mammals, but the first time she saw a bat, “I fell in love,” she said. She went to grad school at Bucknell University, where DeeAnn Reeder has a renowned bat research lab, because of Reeder’s work on WNS, she said.

Brownlee, 23, is interested in animal behavior and studies the differences between white-nose bats and unaffected bats. Last winter, she set up infrared cameras in an abandoned mine and in a hibernation chamber in her lab, and noticed the sick bats were arousing from hibernation every few days, as opposed to every 13 or 14 days like healthy ones. She believes the fungus causes an itchy irritation that wakes the bats up, and she wanted to see whether they spent more time grooming themselves. They did, and they also spent more time crawling around, stretching and yawning, she said. They moved so much that she had to keep rearranging her cameras to get the best angle (she could move them remotely, which doesn’t disturb the bats). This winter, she has more cameras installed in a mine known to be infected with white-nose.

After Brownlee graduates in May, she hopes to find a job as a field researcher or bat biologist working for the government or a non-profit group. She said sometimes she feels like her research is narrowly focused — “On the big scale of this planet, I’m studying bats; what is that about?” — but on the other hand, she’s glad to be working in a field with such major problems.

“It’s highly depressing — we know so little, and with all I do, there are more questions. But I like telling people what I’m doing and trying to make headway into what’s going on,” she said.

Kristin Jonasson, a graduate student at the University of Winnipeg, is studying the different hibernation behaviors of male and female bats, and notes that her findings may have implications for post-white-nose recovery of several species. Female bats have to conserve more fat over the winter so they’re plump enough to produce milk for their pups in the spring, and Jonasson said those fat reserves could also help them survive WNS. No one has ever studied the sex ratio of white-nose survivors, and Jonasson believes more data could help researchers understand population recovery.

Jonasson, 25, will defend her master’s thesis a month from now, and plans to pursue a PhD next. She is starting to look at possible schools and she knows white-nose research will be in demand; this fact is evident just from the content of this year’s bat conference. Nearly half of the 150-plus abstracts at the North American Society for Bat Research symposium mention white-nose in some way, about twice the amount as last year. Interest in bats, and the need for researchers, has grown as the disease has spread. This thrills older researchers like Hicks, who praised Brownlee’s and Jonasson’s work.

“These aren’t million-dollar projects; they are small problems, but every one answered this one tiny piece,” he said. “It’s important research, and nobody else is doing it.”

Two years ago, when Jonasson started graduate work, white-nose was still a brand-new problem that had yet to reach the western United States or Canada. But she knew population studies and baseline data would be important when the fungus eventually reaches her region, and she tailored her research to fit those needs.

“When there’s a massive decline like white-nose, maybe you shouldn’t do exactly what you love — there are more things that need research,” she said. “I still love this, but it’s an area that needs help.”

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