Signs of devastating bat disease found in two Minnesota caves
A fungus dangerous to bats has been confirmed at Soudan Underground Mine State Park and Forestville/Mystery Cave State Park, according to the Minnesota Department of Natural Resources (DNR).
The fungus is known to cause white-nose syndrome (WNS), a disease that is harmful and mostly fatal to hibernating bats, and has decimated bat populations in the eastern portions of the United States and Canada.
The DNR will step up its efforts to slow the spread of the fungus. While the disease is transmitted primarily from bat to bat, fungal spores may be inadvertently carried to caves by humans on clothing and caving gear. The syndrome is not known to pose a threat to humans, pets, livestock or other wildlife.
While only a few bats have tested positive for the fungus, the discovery has serious implications. If Minnesota follows trends of other states, the disease is likely to be present in Minnesota bats within two to three years.
"This is bad news for an important mammal in our ecosystem," said Steve Hirsch, director of the DNR's Ecological and Water Resources Division, which oversees the agency's nongame wildlife program. "We're prepared with special protocols to help keep the fungus from spreading."
Public tours of Soudan Underground Mine and Mystery Cave will continue, but visitors will begin each tour with a brief lesson on how they can prevent the spread of the fungus.
After tours, visitors will be required to walk across special mats designed to remove spores from footwear. They will be advised not to visit other caves or mines with any clothing, footwear or gear they have used in areas where WNS or the associated fungus is present because washing alone cannot sufficiently disinfect clothing.
Ed Quinn, natural resource coordinator for the DNR's Parks and Trails Division, said, "Education is one of the most effective tools we have to slow the spread of the disease."
DNR nongame biologists and park managers have been working for several years with the U.S. Fish and Wildlife Service and leading bat researchers to learn more about and prepare for the disease.
The DNR's actions are consistent with the National White-Nose Syndrome Decontamination Protocol, part of a nationwide effort to slow the spread of the disease. The DNR urges owners of private caves to learn about WNS and take similar visitor precautions as outlined in the protocols.
Sampling for the fungus at the two parks occurred in 2012 and 2013. Recent testing to track the spread of the disease found that four bats of 47 sampled were positive for the fungus. Testing was part of a national study funded by the National Science Foundation and led by researchers at University of California Santa Cruz and Northern Arizona University.
Minnesota has seven species of bats, four of which hibernate during the winter and are at greatest risk of contracting the disease. Mystery Cave, located in southeastern Minnesota, has about 2,300 bats. Soudan Underground Mine, in the northeastern part of the state, has 10,000 to 15,000 bats.
Gerda Nordquist, a DNR mammalogist, said the DNR will continue to monitor Minnesota's bat populations closely, because healthy bat populations are important both ecologically and economically.
Many species of bats feed voraciously on insects, resulting in an estimated $1.4 billion of savings to Minnesota farmers each year by providing pest control, according to a 2011 article in Science.
WNS is named for the fuzzy white growth of fungus observed on infected bats. In bats infected with the WNS fungus, unusual behavior often will be observed, such as flying during the day in the winter or roosting outside when temperatures are below freezing.
The DNR asks people to help monitor bats statewide.
"If you see anything unusual -- sick or dead bats or bats acting strangely -- at Minnesota state parks or elsewhere, please report it as soon as possible," Nordquist said.
Reports can be submitted online, using the bat observation report on the DNR website, www.mndnr.gov/wns. These reports will be reviewed by DNR staff, and additional follow-up or testing will be conducted, as needed.
Visit these sites to learn more about white-nose syndrome:
Minnesota Conservation Volunteer article, "A Coming Crisis for Our Bats," at www.mndnr.gov (www.dnr.state.mn.us/volunteer/julaug11/white_nose.html).
www.whitenosesyndrome.org (includes a map showing the spread of WNS and a downloadable brochure about the WNS tragedy, "Battle for Bats").
Report dead, diseased bats
Report bats flying during the day, clinging to trees or building exteriors in winter when snow is still on the ground, or showing white fungus on muzzles or wings. Do not handle bats. Call the DNR toll-free Animal Report Line at (888) 345-1730 or go to www.mndnr.gov/reportbats.