Great Lakes bats threatened by mysterious disease

By Jeff Gillies, gilliesj@msu.edu
Great Lakes Echo
June 1, 2009

A mysterious ailment that’s already wiped out more than a million North American bats is headed to critical Great Lakes hibernation sites.

White-nose Syndrome, named for the tufts of fungus growing on the faces and wings of afflicted bats, was first spotted in New York in February 2006. The disease has since spread through New England, Pennsylvania and Virginia. Conservationists worry it could spread as far as Mexico.

“As quick as it has spread, it’s most likely going to hit the Great Lakes region within one to two years, potentially wiping out 90 percent of bats that hibernate in the region,” said Rob Mies, director of the Michigan-based Organization for Bat Conservation.

Millions of bats hibernate in caves and abandoned mines throughout the Great Lakes states and Ontario, said Dave Waldien, co-director of programs at Bat Conservation International in Austin, Texas.

“These are very important states for a lot of our species,” he said.

Bats usually wake a few times each winter to drink, mate, and reboot their immune systems. The fungus could cause bats to wake up too often or stay awake too long, using up stored fat reserves, said Merlin Tuttle, Bat Conservation International’s president and founder.

And that could spell trouble for farmers, foresters, and the overall balance of nature.

“Bats do by night what birds do by day in keeping insects in check,” Tuttle said. “That’s a very important function, and we hope we don’t find out just how important by losing our bats.”

One bat can eat a couple thousand bugs in a night, Mies said.

Among the night-flying insects that bats help control are moths and beetles, some of which are intense crop and forest pests. Between control programs and crop damage, those are “million dollar pests,” Tuttle said.

A legacy of the region’s copper mining history, hundreds of abandoned shafts in the northern Great Lakes states and Ontario play a big role in bat hibernation. The region is short on caves, and mines keep a consistent temperature hospitable to bats.

The deep, serpentine mines in Michigan’s Upper Peninsula are difficult to monitor, but some estimates peg hibernating bat populations found within them to be in the millions, Waldien said.

The Neda Mine in Wisconsin produced iron until 1914 and now holds up to 200,000 hibernating bats, he said. Other Wisconsin mines house 250,000 bats combined.

“It’s a very important piece,” Waldien said. “You walk into some of these mines and the walls are just covered with bats.”

But the caves in southern Illinois, Indiana and Ohio are the backbone of Great Lakes hibernation sites, Mies said. Bats gather in the caves by the hundreds of thousands, and the region is within the range of endangered Indiana and gray bats.

A few decades ago the gray bat was near extinction, but conservation efforts restored the species to the millions.

There had been talk of removing it from the endangered species list, Tuttle said. But the new threat from White-nose could mean that the gray bat will soon be back in serious trouble.

The little brown bat, one of the most abundant bat species in the Great Lakes region, has been hit hard by White-nose, Waldien said. Caves with as many as 200,000 little brown bats have dropped to three or four thousand after the fungus appeared.

Many questions still surround White-nose, Tuttle said. Though the fungus is widely suspected to cause the bat die-offs, that hasn’t been proven. It could just be a side effect.

Bat conservation groups like Tuttle’s are funding White-nose research, including studies on the role of the fungus, how the disease spreads from bat to bat and where it could hit next.

Though bats likely catch the disease from other bats, humans can’t be ruled out as vectors, said David Blehert, a microbiologist working on White-nose at the U.S. Geological Survey’s National Wildlife Health Center in Madison, Wisc.

The U.S. National Forest Service closed thousands of hibernation sites to recreational cavers in May, hoping to keep humans from spreading the fungus.

Blehert likened the disease to an invasive species like the zebra mussel, which has spread across the U.S. despite efforts to regulate ballast water and educate boaters.

“And this one, since its microscopic and could be contained in a little clump of dirt in between the treads in the bottom of your shoe, may even have a greater capacity to spread,” he said.

And it’s not just disease that bats are battling.

Urbanization has eaten up a lot of summer bat habitat, Mies said. With roosting sites like dead trees gone, artificial sites like bat houses in backyards could help surviving bat populations that dodge White-nose bounce back.

And a little human sympathy for an animal with a nasty reputation could go a long way.

“They still need humans to understand their importance,” Mies said. “And then hopefully their populations over time will rebound again.”

White-nose has left much of the bat research community scrambling and demoralized, Waldien said. Scientists in the northeastern U.S. are facing cave floors littered with the animals they’ve spent decades studying.

“I can only empathize with the folks that have watched their lives’ investment laying there in the snow and dead on the floor of a cave,” he said. “And they have nothing to fight it or slow it or understand what to do.”

For more info:

US Geological White-nose site
US Fish & Wildlife Service White-nose site
Bat Conservation International
Organization for Bat Conservation