Behold, the benefits of Ohio’s bat population

Bats have been getting a bad rap for hundreds, maybe thousands of years. 

A Greek playwright referred to a bat from hell coming to suck a camel’s blood in 417 B.C. Bram Stoker cemented their connection to evil when he had Dracula turn into a bat — among other things — in his 1897 novel.

Essential

But contrary to the myths that have built up around them, bats don’t attack humans or get tangled in their hair, and vampire bats don’t suck blood, just lick it. Instead, bats are essential to many ecosystems ranging from rainforests to deserts and are a boon to agriculture.

Bats disperse seeds and pollinate hundreds of species of plants. And because some of them eat roughly their own body weight in insects every night, they reduce crop damage and the need for pesticides. 

According to the U.S. Fish & Wildlife Service, bats eat enough harmful insects to save this country’s corn industry $1 billion a year. While many bat species eat insects, some feed on nectar and pollinate high-value crops like peaches, bananas, cloves and agave, a key ingredient in tequila. 

Still, other species eat fruit and thus disperse seeds. Scientists say they may account for 95% of the seed dispersal responsible for early growth in recently-cleared rainforests.

Further benefits

Funded by the National Science Foundation, scientists have been studying other ways that bats benefit humans. For instance, their use of echolocation — emitting high-frequency sounds that bounce off objects, allowing them to navigate and find prey in the dark — inspired sonar and ultrasound. 

Bats are the only mammals that can fly on their own power, not relying on air currents. Unlike those of birds and insects, bats’ wings fold when they fly, like a human hand, which allows them to do a 180 with just three flaps. Studying the structure and dexterity of their wings may someday help improve the maneuverability of aircraft. 

Bat researcher and neuroscientist Seth Horowitz says even the much-maligned vampire bat may help us in new ways. As they lick the blood that results from puncturing an animal’s skin with their tiny canines, they emit a substance that prevents the blood from clotting. Studying this substance may lead to new ways to prevent or treat blood clots in humans, he said.

Ohio bats

In a video for The Ohio Bat Working Group, Marne Titchenell, Extension Wildlife Program Specialist with The Ohio State University’s College of Food, Agricultural and Environmental Sciences, describes  “A Year in the Life of an Ohio Bat.” 

From April through September, bats need somewhere to sleep or “roost” during the day. After all, they’re nocturnal and fly around and eat all night, she said. 

For the hoary bat — the largest bat species in Ohio — and silver-haired and Eastern red bats, that means hanging upside down in the canopy of a tree. Because they prefer to socially isolate when they snooze, they are called solitary bats.    

Other species like to roost in big groups called colonies. If their resting place is in a forest, they’ll sleep in hollows or holes in trees, or under bark that has pulled away from the trunk. The larger groups are made up of females and are called maternity colonies, while males form smaller bachelor colonies.

However, bats that hang together don’t limit themselves to trees. They can also form colonies under bridges, in the eaves of buildings or barns, or in attics. More on that later.

The colonial species that hang out in Ohio include little brown bats, big brown bats, Northern long-eared bats and Indiana bats. Of the four, all but big brown bats are on the state’s endangered list, Titchenell said. 

Bats mate in the fall but don’t give birth until the following year. Females are able to delay fertilization so that the young, called pups, will be born when insects are available. 

The pups are born in May and June and are pretty chunky, about 20 to 30% of the mom’s body weight. She puts a lot of energy into nursing them until they can fly and catch insects on their own, which takes at least a month. The females only have pups once a year. They can have between one and three, but the number is more often one. That’s because bats can live up to 30 years, “so they don’t have to have so many young per year. They can take their time,” Titchenell explained.

Ohio bats hibernate from October through March, she said. The solitary bats are more likely to migrate further south to do that and some, like the hoary bat, may travel long distances, even to Mexico or Central America. 

Colonial bats may migrate, but don’t travel as far. Some stay in Ohio, hibernating in caves, abandoned mines and crevices in cliff walls, she said. 

Dangers to bats

Some bats want their own space and hibernate alone, while others gather in huge clusters for their winter naps. That’s not a good thing when it comes to white-nose syndrome, a fungus that has killed an estimated five million bats in North America since it was first documented in a popular tourist cave in New York in 2006. Since the fungus comes from Europe, scientists think a visitor brought it to the cave on clothing or equipment.

As bats hibernate, the fungus grows on their muzzles, wings and other body parts, causing skin lesions and, ultimately, death. Studies show that casualties in populations of solitary sleepers level off at some point, but not in populations that hibernate in clusters. 

As if white-nose syndrome isn’t bad enough, those charged with counting the casualties of wind turbines are finding more bats than birds, especially so-called tree bats. Scientists so far have found no explanation. 

Meanwhile, other bat populations are suffering because of loss of habitat or other environmental changes, including declines in insect populations.

Great efforts are being made to conserve bats, including getting a better handle on their numbers and locations. From 2011 to 2020, staff and volunteers with the Ohio Department of Natural Resources Division of Wildlife did acoustic surveys to monitor bat populations in the wake of white-nose syndrome. This year, their methods were changed to follow the standards of the North American Bat Monitoring Network or NAbat, which is designed to monitor 47 bat species on the continent of North America, sending statistics to an international database.

House bats

Since bats are protected in Ohio, it’s important to know what you can do — and when — if you discover a colony of bats in your attic. There are ways to evict them, like bat cones that allow them to go out but not back in. Or, you can make an exclusion device out of mesh netting.

“But it’s important that you don’t close them up, or prevent nursing moms from coming back in and feeding their pups,” said Erin Hazelton, Wind Energy Administrator for the ODNR Division of Wildlife.

In fact, it’s illegal in Ohio to exclude bats between May 16 and July 31, when females might be caring for offspring. That is, unless the Division of Wildlife gives permission.

“If they’re in the house, that’s a different story,” Hazelton said. “We don’t ask people to live with bats. They can have rabies, although the incidence is very low.”

The Ohio Department of Health says if you do find a bat in the house and wonder if it has come in contact with people or pets, call your local health department and an animal control agency so the bat can be captured and tested.

“Our bats need help,” Hazelton stressed. There are things that homeowners and landowners can do, like building bat boxes where bats can roost and females can have pups. The internet is full of instructions, she said.

Sarah Stankavich, a wildlife technician with the DOW who is also part of the Ohio Bat Working Group, made a video on creating a bat garden. In it, she suggests planting native flowers that bloom during the late day or night such as blue vervain, goldenrod, evening primrose and phlox. Bats also like herbs such as mint, marjoram, rosemary, chives and lemon balm, she said.

Bats don’t land to drink, so they need an unobstructed source of water, like a small pond or pool. A birdbath will do, as long as it is full. 

Stankavich advises maintaining large trees, especially if they have cavities or loose bark for roosting, and, if possible, having some natural (unmowed) lawn. Don’t get rid of raked leaves in the fall, but keep them in piles; bats, butterflies, beetles and moths all benefit from leaf litter, she said.

The Ohio Bat Working Group, which has a Facebook page, and Bat Conservation International are good sources of information. They also have more ideas for those who want to help bats be more than doppelgangers for Dracula.