Bats may help against COVID-19

This 2014 video says about itself:

This 48-minute documentary explores the world of bats and the scientists who study them — including the late Donald Griffin, a Harvard zoologist who was the first to describe their echolocation ability in the 1940s. Using 3-D graphics to recreate the bats’ acoustic vision and shooting with infra-red and high-speed cameras, this film offers an exhilarating “bats-eye” journey into the night.

From the University of Rochester in New York State in the USA:

Bats offer clues to treating COVID-19

To combat COVID-19, we need to regulate our immune systems to resemble those of bats

July 9, 2020

Bats are often considered patient zero for many deadly viruses affecting humans, including Ebola, rabies, and, most recently, the SARS-CoV-2 strain of virus that causes coronavirus.

Although humans experience adverse symptoms when afflicted with these pathogens, bats are remarkably able to tolerate viruses, and, additionally, live much longer than similar-sized land mammals.

What are the secrets to their longevity and virus resistance?

According to researchers at the University of Rochester, bats’ longevity and capacity to tolerate viruses may stem from their ability to control inflammation, which is a hallmark of disease and aging. In a review article published in the journal Cell Metabolism, the researchers — including Rochester biology professors Vera Gorbunova and Andrei Seluanov — outline the mechanisms underlying bats’ unique abilities and how these mechanisms may hold clues to developing new treatments for diseases in humans.

Why are bats ‘immune’ to viruses?

The idea for the paper came about when Gorbunova and Seluanov, who are married, were in Singapore in March before COVID-19 travel bans began. When the virus started to spread and Singapore went into lockdown, they were quarantined at the home of their colleague Brian Kennedy, director of the Centre for Healthy Aging at the National University of Singapore and co-author of the paper.

The three scientists, all experts on longevity in mammals, got to talking about bats. SARS-CoV-2 is believed to have originated in bats before the virus was transmitted to humans. Although bats were carriers, they seemed to be unaffected by the virus. Another perplexing factor: generally, a species’ lifespan correlates with its body mass; the smaller a species, the shorter its lifespan, and vice versa. Many bat species, however, have lifespans of 30 to 40 years, which is impressive for their size.

“We’ve been interested in longevity and disease resistance in bats for a while, but we didn’t have the time to sit and think about it,” says Gorbunova, the Doris Johns Cherry Professor of Biology at Rochester. “Being in quarantine gave us time to discuss this, and we realized there may be a very strong connection between bats’ resistance to infectious diseases and their longevity. We also realized that bats can provide clues to human therapies used to fight diseases.”

While there have been studies on the immune responses of bats and studies of bats’ longevity, until their article, “no one has combined these two phenomena,” Seluanov says.

Gorbunova and Seluanov have studied longevity and disease resistance in other exceptionally long-lived animals, including naked mole rats. One common theme in their research is that inflammation is a hallmark of the aging process and age-related diseases, including cancer, Alzheimer’s, and cardiovascular disease. Viruses, including COVID-19, are one factor that can trigger inflammation.

“With COVID-19, the inflammation goes haywire, and it may be the inflammatory response that is killing the patient, more so than the virus itself,” Gorbunova says. “The human immune system works like that: once we get infected, our body sounds an alarm and we develop a fever and inflammation. The goal is to kill the virus and fight infection, but it can also be a detrimental response as our bodies overreact to the threat.”

Not so with bats. Unlike humans, bats have developed specific mechanisms that reduce viral replication and also dampen the immune response to a virus. The result is a beneficial balance: their immune systems control viruses but at the same time, do not mount a strong inflammatory response.

Why did bats acquire a tolerance for diseases?

According to the researchers, there are several factors that may contribute to bats having evolved to fight viruses and live long lives. One factor may be driven by flight. Bats are the only mammals with the ability to fly, which requires that they adapt to rapid increases in body temperature, sudden surges in metabolism, and molecular damage. These adaptations may also assist in disease resistance.

Another factor may be their environment. Many species of bats live in large, dense colonies, and hang close together on cave ceilings or in trees. Those conditions are ideal for transmitting viruses and other pathogens.

“Bats are constantly exposed to viruses,” Seluanov says. “They are always flying out and bringing back something new to the cave or nest, and they transfer the virus because they live in such close proximity to each other.”

Because bats are constantly exposed to viruses, their immune systems are in a perpetual arms race with pathogens: a pathogen will enter the organism, the immune system will evolve a mechanism to combat the pathogen, the pathogen will evolve again, and so on.

“Usually the strongest driver of new traits in evolution is an arms race with pathogens,” Gorbunova says. “Dealing with all of these viruses may be shaping bats’ immunity and longevity.”

Can humans develop the same disease resistance as bats?

That’s not an invitation for humans to toss their masks and crowd together in restaurants and movie theaters. Evolution takes place over thousands of years, rather than a few months. It has only been in recent history that a majority of the human population has begun living in close proximity in cities. Or that technology has enabled rapid mobility and travel across continents and around the globe. While humans may be developing social habits that parallel those of bats, we have not yet evolved bats’ sophisticated mechanisms to combat viruses as they emerge and swiftly spread.

“The consequences may be that our bodies experience more inflammation,” Gorbunova says.

The researchers also recognize that aging seems to play an adverse role in humans’ reactions to COVID-19.

“COVID-19 has such a different pathogenesis in older people,” Gorbunova says. “Age is one of the most critical factors between living and dying. We have to treat aging as a whole process instead of just treating individual symptoms.”

The researchers anticipate that studying bats’ immune systems will provide new targets for human therapies to fight diseases and aging. For example, bats have mutated or completely eliminated several genes involved in inflammation; scientists can develop drugs to inhibit these genes in humans. Gorbunova and Seluanov hope to start a new research program at Rochester to work toward that goal.

“Humans have two possible strategies if we want to prevent inflammation, live longer, and avoid the deadly effects of diseases like COVID-19,” Gorbunova says. “One would be to not be exposed to any viruses, but that’s not practical. The second would be to regulate our immune system more like a bat.”

Bat research critical to preventing next pandemic: here.

Saving Mexican tequila bats

This 2017 video says about itself:

The Strange Link Between Bats and Tequila

As a nectar feeder, the lesser long-nosed bat follows the trail of cactus blooms between Mexico and the U.S. One of the plants it also plays a major role in pollinating is agave, which gives us tequila.

From the University of Bristol in England:

Why it’s no last orders for the Tequila bat

July 6, 2020

Summary: Scientists studying the ‘near threatened’ tequila bat, best known for its role in pollinating the Blue Agave plant from which the drink of the same name is made from, have analyzed its DNA to help inform conservationists on managing their populations.

Native to the Americas, the tequila bat (Leptonycteris yerbabuenae) lives in caves in some of the hottest desert areas in Mexico. Given that bats are highly mobile, and that migratory species tend to mix constantly with other bat populations, it is hard for conservationists to know whether they are protecting the best sites for the tequila bats to roost.

While knowing that some tequila bat populations migrate in Mexico’s spring months to the Sonoran Desert to give birth to their pups and pollinate a variety of plants iconic to the region, including the economically important Blue Agave plant. Other tequila bat populations inhabit Southern Mexico year-round, forming large breeding colonies in the winter months.

This study aimed to help better inform conservationists of the species’ breeding and migratory patterns by determining whether the bats inhabiting Southern Mexico year-round have a similar ancestral origin to those that migrate to the Sonoran Desert.

DNA analysis was necessary to understand how historical events may have shaped current tequila bat populations. But first, an international team, comprising researchers from the University of Bristol, the Centro de Investigación Científica y de Educación Superior de Ensenada and the Universidad Nacional Autónoma de México, had to track down the elusive creatures by travelling to remote caves in Mexico to collect DNA skin samples.

Bat expert, Angelica Menchaca (PhD) from Bristol’s School of Biological Sciences who led the study, said: “Tequila bats are beautiful, especially after they arrive back from feeding as they return covered in pollen, completely yellow, a sign of how important they are to this ecosystem. They are easy to handle, not like other bat species that can be more aggressive.

“However, our expedition to the desert was not without hitches and dangers. We were often hiking in temperatures routinely exceeding 40°C and encountering desert wildlife such as rattlesnakes, scorpions, hares, reptiles and ring-tailed cats along the way.

“Once we located the bat colony, our aim was to collect DNA skin samples from the bat’s wing which heals quickly and doesn’t harm them. We would wait until the bats went out to forage at around midnight and then enter the caves that were filled with thousands of baby bats, all packed together in nurseries, waiting for their mums to return.”

Bats are subject to many threats around the world. Their populations are threatened by habitat loss, their roosts are often disturbed, and people fear them both from myths and as potential disease carriers. Bat-phobia is only increasing in our current climate. However, despite their often-negative press, bats are very valuable to ecosystems and the benefits they bring to our societies including the popular beverage tequila.

After analysing samples, the team were able to identify the bats’ mitochondrial DNA and use this to trace the maternal line of the different populations to understand the ancestral descent of the species.

Explaining the findings, Dr Menchaca added: “Contrary to current practice, our study demonstrates that the species must be managed as two conservation units (CUs) in Mexico. We have shown that tequila bat populations that establish maternity colonies in the Sonoran Desert in northern Mexico show a distinct migratory behaviour, breed during the summer, have specific habitat requirements and belong to a maternal line distinct to their southern counterparts.

“In the present context of an accelerated rate of habitat loss, increased fear of bats and decreased appreciation as ecosystem service providers, understanding how we can help support this important species survive these threats is even more relevant.

“We are studying other differences related to their behaviour and morphology that will also help us understand how these bats adapt to diverse habitats.”

Importantly, this research will be used to help inform conservation management strategies, as the tequila bat is considered “Near Threatened” by the IUCN Red List of Endangered Species.

Bats hunting together, helped by echolocation

This 2013 video is about a velvety free-tailed bat, Molossus molossus.

From the Smithsonian Tropical Research Institute in Panama:

A new social role for echolocation in bats that hunt together

June 19, 2020

Searching for food at night can be tricky. To find prey in the dark, bats use echolocation, their “sixth sense.” But to find food faster, some species, like Molossus molossus, may search within hearing distance of their echolocating group members, sharing information about where food patches are located. Social information encoded in their echolocation calls may facilitate this foraging strategy, according to a recent study by Smithsonian Tropical Research Institute (STRI) scientists and collaborating institutions published online in Behavioral Ecology.

Previous research has identified several ways in which echolocation can transfer social information in bats. For example, “feeding buzzes,” the echolocation calls bats produce to home in on prey they’ve spotted, can serve as cues of prey presence to nearby eavesdropping bats. On the other hand, echolocation calls that bats produce while looking for food, called “search-phase” calls, were not known to transfer social information.

However, for group-foraging bats, coordinating flight in the dark with several other fast-flying individuals may require an ability to identify group members on the wing. If search-phase calls contain individual signatures the bats can perceive, it could allow them to know which individuals are flying near them without requiring specialized signals for communication.

Led by Jenna Kohles, STRI fellow and doctoral candidate at the Max Planck Institute of Animal Behavior in Germany, the research team tested whether search-phase echolocation calls contain information about a bat’s identity, and whether M. molossus can use this information to discriminate among different group members. The team exposed bats to search-phase echolocation calls in a habituation-dishabituation paradigm, a method where an animal is exposed to a repeating stimulus until it no longer reacts to it. Then, it is exposed to a new but similar stimulus to see if it reacts, which would indicate that it perceives a difference between the two stimuli.

“We played echolocation calls from two different bats that were both group members of the subject bat,” Kohles said. “By measuring the responses of the subject bats as we switched between calls from different individuals, we could learn about whether the bats perceived differences and similarities between the calls.”

They found that the bats indeed distinguish between different group members, likely by using individual signatures encoded in the calls. Their results could mean that search-phase calls serve a double function. They not only help bats detect prey, but also convey individual identities to nearby foraging group members. This coincides with the fact that the majority of M. molossus’ auditory cortex is tuned in to these search-phase calls, indicating the importance of processing them.

This finding offers insight into not only the social strategies these bats may use to meet their energetic needs, but also into the evolution of echolocation signals and social communication in bats.

“This study suggests that we may be underestimating the crucial ways social information influences bat foraging success and ultimately survival,” Kohles said.

Bats, better animals than you think

This 8 June 2020 video says about itself:

Why Bats Aren’t as Scary as You Think | Nat Geo Explores

When we think of bats, an unfavorable image often comes to mind. Whether it’s the scary portrayal of them in vampire films and literature or a general fear of how their real-life counterparts might transmit viruses, bats have gotten a bad rap that’s actually more fiction than fact. Take a look at how many common bat misconceptions came about and just how vital bats are to our everyday lives.

Orange nectar bats at Panama fruit feeder

This video says about itself:

Many Nectar Bats Taking Their Evening Meal At The Panama Fruit Feeder – May 23, 2020

Orange Nectar Bats aren’t the only mammals to visit the Panama Fruit Feeder at night, though they are certainly the most active. These bats have unique mouth physiology that allows them to use their muscles, as well as capillary action, to draw nectar from plants and feeders. Their tongues have a pair of grooves, lined many small muscles, that are used to force the nectar up and into their mouths.

New African leaf-nosed bats species discovery

This 2014 video from the USA says about itself:

This short video shows California leaf-nosed bats flying in and out of a cave entrance through a night-vision camera. BLM biologists monitor bat populations by counting the number of bats leaving a cave entrance for a calculated period of time.

Video taken by Sterling White, Desert District Abandoned Mine Lands and Hazmat Program Lead, during a bat survey in the spring of 2014.

From the Field Museum in the USA:

At least four new species of African leaf-nosed bats discovered

April 22, 2020

Summary: Researchers just discovered at least four new species of African leaf-nosed bats — cousins of the horseshoe bats that served as hosts of the virus behind COVID-19. Bats play a big role in our lives — they pollinate crops, eat disease-carrying bugs, and carry diseases themselves — but we know very little about them. The more we know about bats, the better able we’re to protect them and defend ourselves against diseases that they can spread.

Bats play a huge but poorly understood role in humans’ lives — they pollinate our crops, eat disease-carrying mosquitos, and carry diseases themselves. But we know next to nothing about most of these animals. There are more than 1,400 species of bats, and 25% of them have only been recognized by scientists in the last 15 years. For most bats, we don’t really know how they evolved, where they live, and how they interact with the world around them. That lack of knowledge can be dangerous — the more we know about bats, the better able we are to protect them and defend ourselves against diseases that they can spread.

In a new paper in a special issue of the journal ZooKeys focused on the coronavirus pandemic, researchers announced the discovery of at least four new species of African leaf-nosed bats — cousins of the horseshoe bats that served as hosts of the virus that caused COVID-19.

“With COVID-19, we have a virus that’s running amok in the human population. It originated in a horseshoe bat in China. There are 25 or 30 species of horseshoe bats in China, and no one can determine which one was involved. We owe it to ourselves to learn more about them and their relatives,” says Bruce Patterson, the Field Museum’s MacArthur curator of mammals and the paper’s lead author.

“None of these leaf-nosed bats carry a disease that’s problematic today, but we don’t know that that’s always going to be the case. And we don’t even know the number of species that exist,” says Terry Demos, a post-doctoral researcher in Patterson’s lab and a principal author of the paper.

The bats that Patterson and Demos studied are leaf-nosed bats in the family Hipposideridae. They get their common name from the elaborate flaps on skin on their noses that the bats use as radar dishes to focus their calls and help catch their insect prey. The family is spread throughout Africa, Asia, and Australasia but its African members are poorly known to science due to lack of research and political unrest in the areas where they’re found.

To get a better understanding of how the leaf-nosed bats are distributed and how they’re related to each other, Patterson, Demos, and their colleagues at Kenya’s Maasai Mara University and the National Museums of Kenya, and the Field Museum undertook a genetic study of leaf-nosed bats in Africa almost entirely based on museum specimens collected in various parts of Africa over the last few decades. In several cases, supposedly widespread species proved to be several genetically distinct species that simply looked alike — new species hidden in plain sight. These “cryptic species” often look similar to established species, but their DNA hints at their distinct evolutionary histories.

The genetic research indicates at least four new and undescribed species of bats; these new species don’t have official names yet, but they give us a glimpse at how much we still have to learn about Africa’s bats.

Finding new species of animals is always cool, but Patterson and Demos say this discovery takes on special importance in the era of COVID-19. The new species of leaf-nosed bats didn’t play a role in the coronavirus pandemic, but their sister family of horseshoe bats did. The horseshoe bats transmitted the novel coronavirus to another mammal (possibly the endangered, scale-covered pangolins), which then spread the disease to humans. It’s not the first time humans have contracted a disease from bats — they seem more capable of transmission than most other mammals.

It’s not that bats are uniquely dirty or covered in viruses. “All organisms have viruses. The roses in your garden have viruses,” says Patterson. “We worry about viruses when it comes to flu and pandemics, but viruses are part of nature and have been as far back as we go. And many viruses are harmless.” But while all animals carry viruses, bats seem especially good at passing them on to us. It might be because bats are some of the most social mammals, living in colonies of up to 20 million. “Because they huddle together and take care of each other, it doesn’t take long for a pathogen to get passed from one end of the colony to the other,” says Patterson.

The other possible reasons for bats being prone to spread disease can be traced to their ability to fly. “Flying is the most energetically expensive way to get around. If you skin a bat, it looks like Mighty Mouse, they have hardly any guts, they’re all shoulders and chest muscle. They’re incredible athletes,” says Patterson. And since flying is such hard work, they have high metabolisms and strong immune systems, and their DNA is really good at repairing itself when damaged. This extra hardiness means bats can harbor disease-causing agents without getting sick themselves; that same dose can be harmful to humans who come into contact with the bats.

And while these bats don’t normally have much contact with humans, the more that people destroy bats’ habitats and expose themselves to bats through hunting and consuming bat meat, the more likely it is that bats will spread viruses to people. “Unless you try to seek out bats, either to harass them or kill them, it’s very, very unlikely that they’ll infect you,” says Demos.

The researchers also note that while horseshoe bats, not their leaf-nosed cousins studied in this paper, have been tied to the spread of COVID-19, it’s still important to study leaf-nosed bats to help prevent future outbreaks. “Leaf-nosed bats carry coronaviruses — not the strain that’s affecting humans right now, but this is certainly not the last time a virus will be transmitted from a wild mammal to humans,” says Demos. “If we have better knowledge of what these bats are, we’ll be better prepared if that happens.”

The researchers also emphasize that in addition to questions about how the bats could harm humans, we need to make sure that we humans don’t harm bats in hopes of curbing disease. Patterson notes, “These bats have a place in nature and perform essential ecological functions, and we can’t let our terror of COVID cause us to pull apart natural ecological systems.”

Scientists compared the different kinds of coronaviruses living in 36 bat species from the western Indian Ocean and nearby areas of Africa. They found that different groups of bats have their own unique strains of coronavirus, revealing that bats and coronaviruses have been evolving together for millions of years. Developing a better understanding of how coronaviruses evolved can help us create better public health programs for the future: here.

Bat biology, new research

This December 2019 video from the USA says about itself:

Biology of bats

It turns out that warm-blooded animals aren’t warm all of the time! Researchers at Brown University studying the muscles in bats’ wings found that their wings operate at a significantly lower temperature than their bodies, especially during flight. The National Science Foundation-funded team says this shows that warm-blooded animals have a lot more variation in body temperature than expected. That has implications for how animals are moving around, including humans.

Singapore fruit bats suffer from environmental degradation

This July 2018 video is called Lesser short-nosed fruit bat (Cynopterus brachyotis).

From the National University of Singapore:

Even resilient common species are not immune to environmental crisis

Measures of genetic diversity of a fruit bat common in Singapore decreased 30-fold over the last 90 years

December 18, 2019

A recent study by scientists from the National University of Singapore (NUS) revealed that the current biodiversity crisis may be much broader than widely assumed, and may affect even species thought to be common and tolerant of fragmentation and habitat loss.

Specifically, the research team found that the effective population size and genetic diversity of a common fruit bat species — the Sunda fruit bat (Cynopterus brachyotis) — that was believed to remain widely unaffected by urbanisation, has shrunk significantly over the last 90 years. By comparing historic DNA from museum samples collected in 1931 and modern samples collected in 2011 and 2012, the NUS team found a nearly 30-fold reduction in effective population size and corresponding levels of decline in genetic diversity estimates.

“This bat species carries a genomic signature of a steep breakdown in population-genetic diversity. The extreme bottleneck event that led to a reduction in genetic diversity happened some time in the early Anthropocene (around the 1940s) when humans’ impact on this planet became dominant,” explained first author Dr Balaji Chattopadhyay, who recently finished a postdoctoral fellowship at the NUS Department of Biological Sciences at the Faculty of Science.

Understanding the decline in population-genetic diversity of the Sunda fruit bat

An effective pollinator and seed disperser, Cynopterus brachyotis represents an important keystone bat species in Singapore’s ecosystem. This bat species is also widely distributed in human-dominated landscapes across tropical Southeast Asia.

In order to understand the effects of human-mediated changes such as urbanisation on the evolutionary trajectory of Singapore’s population of Cynopterus brachyotis, the NUS team reconstructed and compared diverse models of historic demography. The researchers sequenced and examined over 634 million DNA reads of Cynopterus brachyotis genome and generated multiple datasets for the study.

Their findings suggest that Singapore’s Cynopterus brachyotis population underwent a continuous decline that started approximately 195 generations ago (i.e. 1,600 years ago), and experienced a recent genetic bottleneck — or a sharp reduction in population size — nine generations ago, roughly in 1940. Genetic bottlenecks increase the vulnerability of a species to unpredictable events and can accelerate extinction of small populations. While bottlenecks following human interference have been documented in many endangered species, this study suggests that even common human commensals may not be immune to the effects of bottlenecks.

“Cynopterus brachyotis is a generalist fruit bat that tolerates urbanised settings. As such, it is an unlikely victim of habitat degradation and fragmentation. The unexpected loss in genetic diversity in this common species, largely due to urbanisation and human-mediated changes, indicates that the modern environmental crisis can generate adverse silent effects that only become apparent much later, when the impact of low genetic diversity may take hold in a population,” explained Assistant Professor Frank Rheindt from the NUS Department of Biological Sciences, leader of the laboratory group that conducted the study.

“This phenomenon has been characterised as extinction debt, when actual extinction occurs with a time lag, long after the critical damage was done. Hence, an increased understanding of baseline levels and rates of loss of genetic diversity across organismic groups like Cynopterus brachyotis bats and habitats may, in the future, become imperative for informed conservation action,” he added.

This research was conducted in collaboration with the National Parks Board (NParks) Singapore which supported the sampling of contemporaneous populations of the bats. The findings were published in the journal Current Biology on 16 December 2019.

“Our research also underscores the importance of strong museum collections facilitating the DNA-sampling of time series. More global support is needed for modern cryo-collections, which are generally under-funded,” said Asst Prof Rheindt.

Asst Prof Rheindt is looking to extend the research by investigating multiple other animal species in Singapore and Southeast Asia to better characterise extinction risk.

New nature reserve for Bonaire island bats

This 5 September 2019 video says about itself:

Safeguarding Nature Projects – Bonaire – Caves & Karst Nature Reserve

Julianka Clarenda is visiting Fernando Simal of WILDCONSCIENCE and The Caribbean Speleological Society (CARIBSS) to see the Caves & Karst Nature Reserve.

This project of the Public Entity Bonaire in cooperation with WILDCONSCIENCE and The Caribbean Speleological Society (CARIBSS) is funded by the Ministry of Agriculture, Nature and Food Quality (LNV).

Movie commissioned by DCNA, on behalf of Ministry of LNV, produced by B-onair.

Local authorities of Bonaire island in the Caribbean reported, 17 December 2019 (translated):

Caves & Karst Reserve on Bonaire. The 31-hectare park that comprises a special cave system with a colony of bats is an initiative of the local organization Wild Conscience and the Caribbean Speleological Society. …

Bonaire has around 200 caves, some of which are delivery rooms for the 7 bat species. They contribute significantly to the biodiversity of the island that has been a special municipality of the Netherlands since 2010.

American little brown bat conservation

This 2017 video from Canada is called Endangered Ontario: Little brown bat.

From the Ecological Society of America in the USA:

Bats in attics might be necessary for conservation

Buildings are vital summer roosting places for little brown bat maternity colonies in Yellowstone National Park

November 19, 2019

For the little brown bat — a small mouse-eared bat with glossy brown fur — a warm, dry place to roost is essential to the species’ survival. Reproductive females huddle their small furry bodies together to save thermal energy during maternity season (summer), forming “maternity colonies.” In the face of severe population losses across North America, summer access to an attic or other permanent sheltered structure, as opposed to just trees or rock crevices, is a huge benefit to these bats.

In a new study published in the Ecological Society of America’s journal Ecosphere, researchers with Ohio University, University of Kentucky, and the US National Park Service investigate and describe the conservation importance of buildings relative to natural, alternative roosts for little brown bats (Myotis lucifugus) in Yellowstone National Park.

Yellowstone’s iconic high-elevation landscape provides abundant natural roosting places but not many buildings. The study involved four visitor areas with several buildings that are known to host bold little brown bats, which are among the few bat species that will make their homes in structures that are actively used by people, allowing humans to get up close and personal. Sometimes, the investigation even involved researchers capturing them by hand.

“We occasionally entered attics to look to see if they were occupied by bats,” says lead study author Joseph Johnson, an assistant professor of vertebrate biology at Ohio University. “On these occasions we sometimes took the opportunity presented by inactive bats… We would gently pluck them from the walls and glue a transmitter on them in order to study their thermoregulation, but also to let them lead us to additional roosts.”

Over the summers of 2012-2015, researchers tracked individual bats in the park. Using temperature-sensitive radio-transmitters, the researchers measured roost preferences and body temperature regulation in adult male and female bats roosting in buildings, trees, and rocks.

Their results show that reproductive females roost in attics in the study area on 84% of all days for which they collected data, while males roost exclusively in rock crevices or trees. It appears then that outside of maternity colonies, adult males and non-reproductive females will roost by themselves or in small aggregations.

The idea and study of bats using buildings is not new; people have probably seen bats in buildings ever since humans first started building them. What is new is comparing the benefits buildings provide bats with the benefits of alternative natural roosts. “That was what we did in our research,” Johnson says, “using the challenging environment of Yellowstone National Park as a lens through which to view these benefits. As populations of bats continue to decline in North America, we believe that highlighting the importance of buildings to bats is important for conservation.”

Outside Yellowstone and national parks, people frequently evict bats from their buildings. The removal of bats, especially maternity colonies that allow females to conserve warmth and energy, is a conservation concern as white-nose syndrome (WNS) continues to devastate populations in cave-hibernating bat populations across the continent.

WNS is named for a distinct white fungal growth around the muzzle and on wings of hibernating bats — it is the first known pathogen that kills a mammal host during hibernation. The fungus erodes skin and membranes and causes infected bats to burn through energy and fat reserves twice as fast as healthy individuals, and it essentially results in starvation. WNS fungus only thrives in the cold, damp environments typically associated with underground hibernation sites such as caves and mines, and it only grows on bats when they hibernate during winter. Bats that do survive WNS are particularly weak come spring and summer.

“To date, there have been no signs of WNS in these buildings or in Yellowstone, although the fungus has now been documented both east and west of the Park,” says Johnson. If WNS is present in the study area, the researchers expect to see a sharp reduction in the number of bats present during the summer. “Thankfully,” he says, “we have not seen any such decline as of yet.”

Another complication for little brown bats is a state of body temperature regulation called “torpor.” It can be thought of as a form of hibernation, but on a daily scale. In spring through fall, the little brown bat enters a state of decreased physiological activity. Torpor saves energy for the bat when the ambient temperature gets too cool (yes, even in summer). Instead of expending energy and fat reserves to maintain a constant body temperature, torpor allows the body to cool close to their roost temperature and physiological activity to slow. While in torpor, a bat’s heart rate drops from up to 210 beats per minute to as few as 8 beats per minute.

For a pregnant bat, however, their ability to regulate body temperature decreases. Torpor also slows gestation and delays the birth of offspring, potentially forcing juvenile bats to mature quickly before winter arrives, and therefore decreasing survival rates of new generations.

The study confirms that male bats roosting in rocks and trees largely allow their body temperature to dip close to the ambient temperature. Female bats in buildings, on the other hand, sustain higher body temperatures than males throughout the day, thanks to buildings being more insulated from low ambient temperatures during the middle of the maternity season.

Ultimately, the importance of buildings to bats may be especially great at high elevations and latitudes. The researchers believe that buildings allow for larger populations of little brown bats than would be possible without buildings in these landscapes, and that conservation managers need to evaluate the conservation value of buildings for bat populations as WNS continues to grow and spread.

“This warmth is important for bats during the summer months to help with their reproductive efforts,” emphasizes Johnson. “Bats surviving WNS and trying to recover might benefit from a warm roost tremendously.”