Depictions of bats as blood-sucking beasts with violently flapping wings, high-pitched calls and sinister sleeping positions have induced fears in the public for centuries, but recent research suggests that the winged crusaders are creatures to embrace rather than exclude.

Bats provide a number of benefits to society, both economically and environmentally.

According to Lisa Gatens, curator of mammals for the North Carolina Museum of Natural Sciences, in North Carolina, insectivorous bats eat insects that prey on important agricultural crops, while also allowing farmers to decrease pesticide use. A 2011 study by the American Journal of Science reported that bats contribute about $23 billion to the national economy just by eating insects.

Steve Grodsky, a Ph.D. student in wildlife ecology, said researchers rarely gave much credit to bats for the amount of insects they eat because they initially attributed it to birds, which only feed on insects during the day.

“Bats are the primary insect eaters of the night,” Grodsky said.

Grodsky said bats eat about half of their body weight each night, meaning one million bats consume 694 tons of insects annually.

“Fruit-eating bats help spread the seeds of the fruits they consume, since they take the fruit away from its source in order to avoid any nearby predators,” Gatens said.

Gatens said that nectar-feeding bats increase pollination of plants such as the agave plant, the plant from which tequila originates.

“Scientists also use bats as bioindicators, meaning they provide a measurement for the health of the overall environment given their ‘links’ to the ecosystem,” Grodsky said.

For example, bats occupy a high trophic level in the food chain due to their predator status, allowing researchers to examine pesticide accumulation in bats. As bats consume prey, such as insects, they consume the pesticides absorbed by that specific prey.

“Fewer bats could indicate changes going on in the insect community,” Grodsky said.

Grodsky said that researchers are also investigating how they might use bat echolocation as a model for medical applications to aid the blind with everyday activities.

“Lots of mammals can echolocate, and they all have different structures,” Grodsky said. “People are mammals and potentially humans have the ability to use sonar if you can train your brain to do it. Another possibility is that sometimes when you lose a sense, your other senses become more acute so maybe because they lost their vision, they are more able to use this echolocation, or to visualize it.”

Gatens said she enjoys her work with bats, and students are always surprised by how small and vulnerable they appear to be at first sight.

“I’m always just amazed by them,” Gatens said. “Outside in the woods at night you get to experience nature in a different way.”

A dwindling bat community

In spite of increased insect populations, bat populations are beginning to dwindle due to a fungus known as white nose syndrome.

Widely regarded as the worst ecological disaster of its time,white nose syndrome has killed between five million and seven million bats since 2006. The fungus, pseudogymnoascus destructans, causes white nose syndrome by growing on bats’ skin tissue during hibernation and replacing their fat tissue with fungus tissue, thus depleting their fat reserves.

“They either die from starvation immediately or come out of hibernation early,” Gatens said. “It’s really hard to see if you are someone who has an appreciation for bats.”

Bats with the syndrome have a mortality rate of more than 90 percent, with other symptoms including significant losses in their wing membrane, which impedes flight, fluctuations in homeostasis, an inability to forage and take care of their offspring, as well as dehydration.

According to Gatens, bats hibernating in caves provide the exact environment the fungus needs to flourish, with ideal temperatures ranging from 5-10 degrees Celsius, but not more than 20 degrees Celsius.

Researchers theorize that humans brought the fungus from Europe to New York, which is home to one of the most popular recreational caving sites. Though most species of bat are highly susceptible to the fungus, Gatens said there is good news.

“Some individuals within a species seem to show resistance,” Gatens said. “Tree-roosting bats are immune to the syndrome.”

The human effect on bat populations

However, disease is not the only threat to the success of the bat population. With the proposal to build wind turbines offshore, bats have every reason to be worried.

According to Grodsky, the turbines can kill bats either through direct contact with the spinning blades, or barotrauma, during which bats’ lungs implode due to a drop in barometric pressure, which takes place behind the turbine blades. A study Grodsky worked on found the majority of bat fatalities from wind turbines resulted from direct contact.

Often, ecologists give more attention to bird fatalities from the turbines, but turbines only killed an estimated 200 birds in a two year time frame versus 5,000-6,000 bats, Grodsky said.

“Everyone is worried about the birds because birds are more charismatic,” Grodsky said. “All of a sudden bats are dealing with two fatal situations [white nose syndrome and wind turbines].”

Restrictions can decrease the number of bat fatalities by setting wind turbines at higher speeds than bats typically fly, Grodsky said. The problem is, companies using wind power often dislike this approach because it could result in increased spending.

According to Grodsky, a more cost-friendly approach uses an apparatus that is attached to the turbines and emits ultrasonic waves in a process called “sonar jamming” in order to “mess up” the bats’ sonar to deter bats from going near them.

“However, the best approach is putting turbines where there are less bats,” Grodsky said.

Both Grodsky and Gatens said there are easy ways for humans to aid in preservation of bat populations. 

Bat houses, with the right structure and in the right location, can help the bat population, as well as abiding by rules at caves, such as completing the decontamination process or simply not entering caves closed on public lands.