A little brown bat in New York has white-nose syndrome. The fungus has now been discovered in Michigan. / Ryan von Linden/New York Department of Environment
The moment Michigan bat researchers have expected — but dreaded — has arrived.
White-nose syndrome, an invasive-species fungal disease that is decimating bat populations throughout the eastern U.S. and parts of Canada, has been found in Michigan bat colonies for the first time, the Michigan Department of Natural Resources announced Thursday.
Researchers in February and March found five infected bats in Alpena County in the northeastern Lower Peninsula, and in Mackinac and Dickinson counties in the Upper Peninsula.
The Wisconsin DNR also announced Thursday the discovery of white-nose syndrome in that state.
“Many researchers believe this is the biggest wildlife catastrophe in North America in 100 years,” said Rob Mies, ecologist and head of the Bloomfield Hills-based Organization for Bat Conservation.
The disease affects a bat’s skin and metabolism, causing it to come out of hibernation in winter far more frequently than normal, which makes the bats use up their fat reserves before winter is over — and for a mammal that is less than 4 inches long and weighs about the same as one to three U.S. nickels, there’s little extra fat to work with.
With no flying insects to feed on in February or early March, the bats starve to death. Some affected caves have seen 90% die-offs or more within about two years, scientists said.
“Even though we’ve known this disease was coming, it is a disappointing day,” said DNR wildlife veterinarian Dan O’Brien.
It means the little brown bat, seen so frequently swooping for insects in Michigan’s dusk or early dawn skies, may soon become endangered, or worse — virtually extinct.
Some experts have likened what is coming to the demise of the passenger pigeon, a bird whose sheer numbers once blackened the skies for miles across the U.S., but was brought to extinction through over-hunting by 1900.
“I say this is worse than the passenger pigeon, because it involves multiple bat species,” said Allen Kurta, a bat researcher from Eastern Michigan University who discovered white-nose syndrome in Michigan bats earlier this year.
And many fewer bats means many more insects.
A single bat eats about 5,000 insects per night. A 2012 study in the journal Science found that bats provide farmers in Michigan with $508 million worth of insect control each year, and $23 billion worth annually across the U.S.
Bats are the primary predator of nocturnal flying insects, and without them, the ecological impacts are still unknown, researchers said.
“We really don’t know what’s going to happen because something of this magnitude and scale has never occurred,” Kurta said.
“You would expect it to upset the equilibrium,” added DNR wildlife biologist Bill Scullon. “This is so new into the science of the phenomenon that they are just now beginning to study that in places in North America where the disease has been for about five years.”
1st signs of fungus
The fungus causing white-nose syndrome was brought to the U.S. from Europe by unknown means around the winter of 2006-07. It was first discovered at Howe Caverns near Albany, N.Y., a popular site for visitors.
“Someone probably used boots or gear from visiting caves in Europe and soil with dormant fungus dropped off,” Mies said.
Many species of bat, including the little brown bat, huddle close together in underground caves during winter hibernation, using each other’s body heat to keep their temperatures a little above freezing. That caused the fungus to spread from bat to bat. And, as they migrated, spores were carried into ever-widening areas.
“If you take a map of cave systems in the United States, and then look at a map of the spread of the disease, they are almost identical,” Kurta said. “They went through New York, Pennsylvania, down the Appalachian Mountains, then took a turn westward into the Ohio River Valley.”
Lakes Huron and Superior likely acted as buffers — at least temporarily — holding back the disease.
Michigan’s lack of cave systems may have also slowed the spread to this state. Michigan bats, however, have adapted to using the hundreds of old mining shafts in the Upper Peninsula as substitute caves. So, the disease’s arrival was only a matter of time.
Kurta, who has studied Michigan bats since 1978, began surveying hibernating bats for the DNR in 1996. The discovery of white-nose syndrome in the U.S. in 2008 added a new urgency to the surveys, he said.
The fungus hasn’t wiped out European bats because they have had tens of thousands of years to adapt, Kurta said.
“A colony of 100 to 300 hibernating bats is a fairly large colony in Europe,” he said. “But we have colonies in Michigan of 50,000. You can go other places in the U.S. where the colonies can be 100,000 bats, 300,000 bats.”
'Like thin cotton candy'
The DNR is withholding where, specifically, the infected bats were discovered in an effort to keep people away from the sites: Further disturbance to already-infected bats could lead to even wider die-offs, according to biologists.
Kurta said he discovered the first infected bat in Michigan earlier this year in Dickinson County almost by luck.
“Something didn’t look right; I pulled the bat down and unfolded its wing,” he said. The fungus on the wing “looked like thin cotton candy.”
The fungus’ attack on a bat’s skin creates changes that give off a luminescence under ultraviolet light.
“Just by practice we checked that bat and we were stunned,” Kurta said. “It was the first time one of the bats glowed that yellow-orange color.”
Weeks later, at sites in Alpena and Mackinac counties, the presence of the disease “was obvious as soon as we walked in,” he said.
No die-offs are present yet, but Kurta knows they are coming. The bats will return to their hibernating spots next winter, and the fungus spores will be waiting for them. It will be worse next winter, he said.
White-nose syndrome has killed at least 5.7 million bats in the eastern U.S. in the past seven years. The breathtaking pace of the disease’s spread has researchers reeling.
“People who work with bats are very close to their animals,” Kurta said. “It’s like every member of your extended family just got a terminal diagnosis. I’m still coming to grips with it. And it will be a couple of years before the disease becomes as deadly as it will be here.
“Last winter, I could have taken you into places where thousands of these little, tiny creatures were peacefully hibernating. If we go back there three years from now, there will probably be only a handful.”
The DNR will continue to monitor bat hibernation sites, and is re-emphasizing prohibitions on people entering underground sites on DNR-managed land, Scullon said.
At known bat sites in abandoned mines, the DNR will install gates allowing the bats to leave but no people to enter.
Research into the disease is ongoing. Some nontoxic fungicides have shown promise, as have artificial bat caves where the fungus can be better managed, Mies said.
But how to treat millions of tiny, free-flying mammals? How to find every mold-infested cave or old mine shaft?
“There’s a lot of things going on in the lab, but getting something that’s field-deliverable is a different story,” Scullon said.
Saving the little brown bat and other species in North America ultimately may be hopeless, but researchers aren’t giving up hope.
“I don’t think anybody’s exuding confidence, but there are people who are trying. That’s the main thing,” Kurta said. “And you have to try.”
Contact Keith Matheny: 313-222-5021 or email@example.com