Research & Scholarship

Not so spooky: Bats are beneficial – and they’re in trouble

A W&M visiting professor and undergraduate researchers are actively aiding bat conservation efforts.

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Published October 21, 2024
An orange and black painted bat roosts on a twig among green leaves.

Painted bats live in nuclear families consisting of two parents and an offspring. They roost in banana tree leaves, under the eaves of huts and in suspended nests of weaver finches and sunbirds. Their orange and black coloration may be a form of camouflage that helps to protect them when they roost in dead banana leaves. Online sales of taxidermied painted bats is believed to be taking a toll on already declining populations. Photo by faridmuzaki via iNaturalist

Ironically, the painted bat’s protective orange and black camouflage makes it stand out to predators who would likely never spot it in its natural habitat. 

Internet-surfing Halloween decorators and wildlife collectors are fueling a growing trade in the preserved corpses of this near-threatened species, adding to the number of threats faced by declining bat populations worldwide.

Although painted bats are caught and killed in their home range of southeast Asia, western nations are driving the market. The lion’s share of buyers are located in the United States, and many purchasers are unaware that the sellers’ claims of sustainable harvesting are false. Experts agree that these specimens are collected from declining wild populations.

Dave Waldien is a visiting assistant teaching professor in William & Mary’s Department of Biology who has specialized in bat conservation for more than 25 years. He is currently mentoring a group of undergraduate students who are contributing to bat conservation research. Hands-on research experiences like these give W&M students the opportunity to work closely with faculty like Waldien as part of the university’s efforts to provide the most personal education of any public university in the United States.

“My interest in bats goes all the way back to when my mom read the book “Stellaluna” to me as a little kid,” said Charlotte Toomey ’26. “Now that I’ve had the opportunity to get involved with research on campus, I’ve learned how bats like Stella are vital to ecosystems around the world, and I’m able to contribute to bat conservation efforts.”

With an average wingspan of 4 to 5 feet, the Indian flying fox is one of the largest bat species in the world. Like many other bats that consume fruit, flowers and nectar for sustenance, this bat plays a valuable role in pollination and seed dispersal. Often regarded as a pest, this species is threatened by persecution from humans, habitat loss and being harvested for its perceived medicinal value. (Photo by G. VIGO via iNaturalist. CC-BY-NC)

Beneficial bats

“Bats are really unique and special,” said Waldien. “They do many amazing things that are valuable to ecosystems and to humans.”

For example, many species of bats are voracious insectivores. Here in the United States, the furry fliers save farmers billions of dollars in pest control costs every year.

In the tropics, nectar-sipping bat species pollinate crops like bananas, avocados, mangos and agaves, including agaves that are used in tequila. Worldwide, more than 300 species of fruit depend on bats for pollination.

Fruit-eating bats, meanwhile, disperse a wide variety of seeds, including those of nut, fig and cacao trees. With a dispersal range of up to 75 kilometers, bat-aided seed distribution plays a key role in forest regeneration and maintaining the genetic diversity of trees and crops. 

Waldien also notes that bats are fascinating in and of themselves. With more than 1,460 species of bats around the world, they’re incredibly diverse.

“Some weigh about as much as a penny,” he said, “and others have a wing span approaching five and a half to six feet. Some of them look like little puppy dogs, and others have other unique appearances due to physical modifications for acquiring different types of food.”

A lesser long nosed bat is poised above a cactus flower.
Described by the National Park Service as “connoisseurs of cactus,” lesser long-nosed bats use tongues as long as their bodies to sip the nectar of cactus blossoms that they find by scent. They also eat the fruit of these species, thereby providing both pollination and seed dispersal for these desert plants. Sometimes referred to as the tequila bat, this species is the face of a campaign for bat conservation through bat-friendly tequila. (Photo by Scott Buckel via iNaturalist CC BY-NC)

Bats are also nimble fliers with a penchant for aerial gymnastics. Chiroptera is the order that encompasses all bat species. The name translates to “hand wing,” a description of the complex structure of bat wings that resembles a modified human hand and contributes to their agile mid-air maneuvers.

“They’re amazingly acrobatic in their flight patterns,” Waldien said. “Some of them just do loops around you.”

Bats’ aerial feats have inspired new drone and robotic technology, while their echolocation abilities have influenced the development of compact, efficient sonar systems and ultrasonic canes to aid the visually impaired.

Globally, bat populations are declining

Mature females of most bat species produce only one pup per year. This slow reproductive rate is a major factor in the vulnerability of global bat populations to a range of ongoing threats, including climate change, collisions with wind turbines, persecution spurred by fear and misinformation, hunting for the bushmeat trade and unsustainable guano harvesting.

Introduced diseases also take a toll. For example, white nose syndrome, a fungus from Europe, has killed millions of bats in North America, including approximately 90% of three once common species. Since it was first detected in New York in 2006, the disease has spread to 40 U.S. states and eight Canadian provinces.

Waldien explained that the largest driver of bat population declines, however, is habitat loss – particularly due to deforestation and decreased availability of cave roosting sites. Habitat provides species with food, water, shelter and places to raise young, so the loss of these areas has significant impacts on the species who depend upon them.

While all bats drink on the wing, some species like this grey-headed flying fox also skim the water to lower their body temperature on hot days. In the case of this species, the behavior can be necessary for survival, but also poses a risk of predation by crocodiles. Fires and extreme heat events in Australia killed huge numbers of this species, and they are listed as vulnerable on the Red List, which is comparable to threatened under the U.S. Endangered Species Act. (Photo by  Ákos Lumnitzer via iNaturalist CC-BY-NC-ND)
Named for the suction cup-like disks on its hind legs and feet that allow it to cling to and move along slick surfaces, the Spix’s disk-winged bat roosts in furled leaves, which requires specialized habitat. (Photo by Rich Hoyer via iNaturalist CC-BY-NC-SA)
Vampire bats are native to the Americas and can be found from northern Mexico to South America. Unlike most other bats, these bats can walk, run and jump, which aids them in sneaking up on their prey, such as sleeping cows and birds. To feed, they make a tiny incision with their teeth and lap up a small amount of blood that flows out of the cut. Draculin, the anticoagulant in vampire bat saliva, is being studied as a potential treatment for blood clots in stroke victims. (Photo by  nachobarragan via iNaturalist CC BY-NC)

In order to aid in preserving habitat for bats, Waldien works to ensure that bats are considered when key biodiversity areas (KBAs) are identified. Pinpointing these hotspots of biodiversity helps governments to determine which lands to prioritize for conservation.

“KBAs are identified through scientific global standards and are important to biodiversity conservation,” said Waldien. “We’re mobilizing and catalyzing the global bat-expert  community to get involved and to ensure that bats are considered when KBAs are updated.”

A key tool in determining KBAs is The International Union for Conservation of Nature’s Red List of Threatened Species, which inventories the global conservation status and extinction risk of biological species throughout the world. Waldien serves as the Old World Bat Coordinator for the Red List Authority and coordinates and completes assessments with bat researchers and students around the world — including here at W&M. 

For conservation to succeed, he explained, it’s essential to work with local communities, and long-term relationships are the most productive as they help ensure a project is sustainable.

“If you treat people with respect, listen to their concerns and engage with them based on their culture, then they respond very well to conservation efforts,” he said. 

Five Honduran white bats with bright yellow accents line up back to front within a large green leaf.
Honduran white bats cut leaf ribs with their teeth to create tent-like structures to roost in during the day. This bat is highly specialized and depends almost exclusively upon one species of fig for food. The mechanism behind the deposition of carotenoids in its ears, nose-leaf and lips is being studied to more deeply understand and possibly combat macular degeneration in humans. Habitat loss is the main reason for this species’ decline, and it is listed as near-threatened by the IUCN. (Photo by caseytunia via iNaturalist CC BY-NC)

Student bat conservation research

Anika Srikanth ’25 is developing a geospatial map that supports an Indigenous initiative to update a KBA in Bougainville, Papua New Guinea. The local clans have established three zones to guide management of their resources, including tambu (sacred), traditional use and community use areas. Working with the local people, Srikanth and Waldien will propose the update to the KBA.

Meanwhile, 10 other students are updating Red List assessments. Their work involves collating information and navigating a challenging writing process to present the information that they’ve gathered to the IUCN.

Charlotte Toomey ’26 is working on a Red List assessment of the long-haired fruit bat, a megabat native to Africa, and has also recently begun reviewing data for a project evaluating bat use of mine culverts in Mexico.

“My particular research on bat use of culvert-gates in mines enables cave-roosting species to make use of the vital habitat without human disturbance,” said Toomey, “and my work on assessing the long-haired fruit bat for the IUCN Red List provides a framework for how to improve conservation efforts and builds upon pre existing ecological data.”

A great fruit-eating bat snacks on a green fruit while hanging upside down.
Humans are studying unique membranous structures in the heart of the great fruit-eating bat to possibly aid in keeping the heart in the correct position while upside down, flight assistance, and energy reservation. The insecticide deltamethrin has been linked to reproductive problems in this species. (Photo by Antonio Amaral via iNaturalist CC BY-NC)

How can non-scientists help bats?

First and foremost, said Waldien, bats need ambassadors to raise awareness of their importance, dispel myths and promote conservation of bats and their habitat.

As all of the bats in the Williamsburg area eat night-flying insects, W&M bat enthusiasts can provide local habitat by planting a bat garden with night-blooming native plants to attract moths and other nighttime insects. In addition to nectar-producing flowers, it’s best to include host plants to feed moth caterpillars, thus ensuring a steady supply of prey. Minimizing pesticide use can also help to ensure that bats have plenty of healthy snacks to devour. 

Nighttime lighting has been linked to declines in insect populations, which in turn decreases bats’ food supply. Additionally, when bats hunt insects that are attracted to outdoor lighting, the bats are more visible to predators. Thus, turning off lights at night or using motion detectors makes areas more bat-friendly.

Installing a bat house can be another effective way to provide habitat for bats, as these structures provide a safe roosting spot for female bats with pups.

Experts advise observing wildlife from a respectful distance. In the event that someone finds an injured or sick bat, the best course of action is to contact a permitted wildlife rehabilitator for assistance. For the protection of both bats and humans, it is important not to handle bats.

Once one of the most common bat species in North America, the little brown bat is now listed as endangered due to the spread of white-nose syndrome. In the northeastern U.S., more than one million of these bats died from the fungus between 2006 and 2011. Winter hibernacula populations declined up to 99%. (Photo by Jason Headley via iNaturalist CC BY-NC)
The eastern red bat is native to eastern North America. These bats have been found hibernating under leaf litter in the eastern U.S., though for the most part, they migrate south for the winter. Although they eat many types of insects, they prefer moths, including invasive species like gypsy moths. (Photo by Ed O’Connor via iNaturalist CC BY-NC)
The Rafinesque’s big-eared bat eats mostly moths, but also preys on mosquitoes, beetles and flies. According Texas Parks and Wildlife, when these bats rest, they coil their ears against their heads “like rams’ horns to reduce their ears’ surface area and conserve body moisture.” This bat is listed as vulnerable in the U.S. and Canada. A large driver of its decline is likely a lack of the large hollow trees in which it has historically roosted. (Photo by Ted Weber CC BY-NC)
The hoary bat is widespread throughout North America. It’s a long-distance migrant that spends winters in Central America and the southwestern U.S. and warmer months further north in the U.S. and Canada. Hoary bats are one of the species most affected by collisions with wind turbines. (Photo by Aldo Ortíz Reyes via iNaturalist CC BY-NC)

This Halloween and every day, Waldien advises taking a closer look at the benefits of bats and learning to appreciate them for their innate charms as well as the services that they provide.

“Even when you look at our local Virginia bats,” he said. “They may seem unremarkable because they’re small and uniform in color, but their capabilities are what won me over. Educate yourself on the diversity of bats around the world, their distinctiveness and their abilities. Never handle them, but be aware of them and get to know them for the special creatures that they are.”

, Research Writer