Fungus, wind turbines, habitat loss threaten Mich. bats

Charles E. Ramirez
The Detroit News

Michigan’s bats are under siege from natural and man-made threats that could wipe out some populations over the next decade, experts warn.

Disease-causing fungus, wind turbines and loss of habitat are harming the small, furry creatures in the state, which is home to nine different species.

“Those are the three biggies,” said Allen Kurta, an author, Eastern Michigan University biology professor, researcher and bat expert. “But I would say (the disease caused by the fungus) is probably the biggest threat.”

Pseudogymnoascus destructans is a fungus attacking the webbed-winged mammals in Michigan and 28 other states, causing a disease called white-nose syndrome.

The white fungus, which came from Europe, thrives in cold environments where bats hibernate. It also grows on a bat’s skin, damaging it and forcing the animal to frequently wake up from hibernation. Bats with the disease use up their fat stores before winter ends and starve to death.

“They’re under a lot of stress,” said Rob Mies, executive director of the Organization of Bat Conservation in Bloomfield Hills, which operates Bat Zone, a live animal center designed to teach the public about bats and other nocturnal animals at the Cranbrook Institute of Science.

“Stress is bad for humans. And just like us, it’s bad for bats.”

The disease, which only affects bats, was first detected in North America in New York in 2007. It was first found in five bats in five counties — Alpena, Dickinson, Keweenaw, Mackinac and Ontonagon — in northern Michigan in 2014. Since then, it’s spread to 11 counties.

Kurta said the disease has mostly affected bat species that hibernate underground or in caves.

State officials have identified five species — big brown bats, little brown bats, northern long-eared bats, tri-colored bats and Indiana bats — as the bats in Michigan most susceptible to the disease.

Kurta predicts the disease could wipe out a couple of the state’s species of bat in the next decade.

“I think it is quite likely we will lose one or two species, particularly the northern long-eared bat, in the long run,” he said.

“We could see it go extinct in the Northeast within the decade. No one I know is giving the species much of a chance.”

The U.S. Fish and Wildlife Service also has designated the northern long-eared bat as a threatened species.

Wind turbine fatalities

Meanwhile, wind turbines are also killing bats in Michigan because the creatures collide with the spinning blades.

Bats that migrate south for the winter are being affected by wind turbines and researchers are trying to figure out why.

Michigan has 887 wind turbines, mostly in the Thumb, according to the American Wind Energy Association, a Washington, D.C., trade association.

American Wind spokesman David Ward said the group and its members are working to reduce the number of bat fatalities caused by wind turbines.

Last year, the association developed its best management practices expected to reduce the impact of wind turbines on bats by 30 percent, he said.

Under the voluntary protocols, turbine operation is limited in low-wind speed conditions during the bat migration season in the fall.

Seventeen companies across North America — including CMS Energy in Michigan — have agreed to implement the protocols, according to the association.

Critical numbers

Bats are critical to ecosystems around the world and in Michigan, experts say.

Some bat species aid in the pollination of trees and flowers. Others eat fruit and spread seeds to other areas.

But the diet of most bats consists of insects. As a result, the critters contribute between $528 million to $1.2 billion in pest control to Michigan’s agricultural industry, according to the state Department of Natural Resources.

But their environments continue to shrink because of climate change, man-made development and fungus.

“There’s also a huge loss of habitat,” Mies said. “And the bigger issue is bats only have one baby a year, and we think only 10 percent of their babies make it to a year old. The population rebounds very slowly. It can take centuries.”

But the bat situation isn’t completely hopeless, he said.

There’s a chance, Mies said, bats will learn to roost in places free of the fungus. Also, scientists have made progress developing treatments to help bats survive the fungus.

“Bats are intelligent animals,” Mies said. “I don’t think it’s too late for humans, and I don’t think it’s too late for bats, but we do need to make some changes.”