A devastating fungus that kills hibernating bats has been found for the first time in Wisconsin in an abandoned mine in Grant County, state officials announced Thursday.
White-nose syndrome was discovered in bats last month while Department of Natural Resources personnel were inspecting an old mine site in southwestern Wisconsin, the agency said. The state is home to one of the largest populations of hibernating bats in the Midwest. An estimated 350,000 to 500,000 bats use caves and mines before dispersing in the spring to Minnesota, Illinois, Indiana, Iowa and Michigan.
The finding has wide-ranging implications, especially for agriculture, because of bats’ voracious insect-eating ability. A single little brown bat can consume 600 mosquitoes in an hour.
A 2011 study examined the economic impact of bat populations and concluded that in Wisconsin alone bats provided an annual benefit ranging between $658 million and $1.5 billion.
The fungus causes bats to awake while hibernating. Flying and other movements deplete energy stores and cause dehydration before spring.
White-nose syndrome poses no health threat to humans, the DNR said.
A few hours after the Wisconsin DNR’s announcement, the Michigan Department of Natural Resources said white-nose syndrome had been discovered in three counties — Dickinson and Mackinac counties in the Upper Peninsula and Alpena in lower Michigan.
The announcements bring to 24 the number of states with the disease.
White-nose syndrome has killed more than 5.7 million bats in the United States and eastern Canada, according to estimates. It was first found in New York in 2006.
“A day we had long dreaded has arrived,” DNR Secretary Cathy Stepp told agency personnel in an e-mail this week.
She said the finding appeared to be an isolated incident, but experts believe once the fungus is detected, bat mortality will grow. Mortality in caves in other states has reached 95%, she told employees.
The DNR has been conducting winter surveillance to look for evidence of the disease. It was wrapping up a sweep of 85 hibernacula when employees found telltale evidence of the disease in 11 bats in the Grant County cave. White fungus was found on the muzzle of the bats and other body parts.
Laboratory results confirmed the disease in two species — little brown and northern long-eared bats.
The same site was inspected last year, but revealed no sign of the disease, according to Erin Crain, director of the state Bureau of Natural Heritage Conservation. An estimated 700 bats were hibernating there. Most were little brown bats.
The disease is transmitted when bats come into contact with the fungus or an infected bat.
“We’re not surprised,” Crain said. “We knew this was coming.”
Crain said she expects bat populations to decline beginning in 2015.
David Blehert, a microbiologist with the federal National Wildlife Health Center in Madison, said the trend in other states has been higher bat mortality in the second and third years after detection.