America’s bats are dying. A Michigan dam may hold a key to their survival


The inside of a healthy hibernaculum should be virtually motionless. Instead, the video shows bats flying about or writhing on the ceiling as they try to lick fungus from their skin. Some fall exhausted to the floor, where they drown in puddles or are eaten by rodents. 

The U.S. Fish and Wildlife Service declared the northern long-eared bat to be endangered in November, in a decision agency director Martha Williams called “an alarm bell and a call to action.”

Meanwhile, the Indiana bat, listed as endangered throughout the eastern U.S. since the 1960s, is inching closer to extinction. Little browns are being evaluated for potential listing, and the tricolored could be listed this year. Experts are hopeful that some populations of little brown and tricolored bats will persist because their range extends into the southern U.S. and Latin America, where the cold-loving Pseudogymnoascus destructans can’t kill them as easily.

Policy changes, such as putting caves off-limits to human visitors, are of limited use, as white-nose continues to spread on the wings of the bats themselves. 

That leaves scientific breakthroughs as the bats’ best hope. 

The search for answers at Tippy Dam

After white-nose syndrome arrived in the U.P. mines, Kurta went back to Tippy Dam expecting to find similar carnage. Instead, a few northern long-eared bats had died, but tens of thousands of little browns appeared mostly unaffected. 

Still, his heart sank. He assumed the fungus would soon take over.

“I firmly believed that the next time I came, they would have been all dead,” he said.

Instead, the bats have persisted year after year. Now, scientists are scrambling to understand why.

The first question, Kurta said: “Is it genetic, or environmental?”

In December, he collected 30 bats from inside the spillway and sent them to the National Wildlife Health Center in Madison, Wisconsin, along with 30 bats from a U.P. mine. Each has been swabbed with the fungus, then left to hibernate in a controlled environment. 

If the Tippy bats fare better than their U.P. counterparts, they probably have a genetic resistance to white-nose syndrome, said Tonie Rocke, a research epidemiologist at the Wisconsin center. 

If they die, something about the dam must be keeping them alive.

Given the emergency facing bats afflicted with white-nose, Rocke said, the wait for answers can be agonizing. 

“You feel a lot of pressure sometimes to move faster,” Rocke said. But science is meticulous for a reason. “It’s important to confirm that what we might do will work, before we apply it haphazardly.”