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Statewide survey detects no evidence of white nose syndrome in Michigan bats

Michigan DNR surveyed caves statewide in search of bat species

DETROIT – A recent survey of 60 sites, where bats overwinter in Michigan, found no sign of white nose syndrome, the Department of Natural Resources said.

White nose syndrome (WNS) is an invasive fungus fatal to bats. The fungus infects a bat's skin and causes the bat's energy reserves to deplete before the hibernation period is over.

The survey – conducted by DNR Wildlife Division staff in conjunction with Dr. Allen Kurta and Steve Smith of Eastern Michigan University – involved of caves and abandoned mines across the northern Lower Peninsula and Upper Peninsula. These survey locations represent the major bat colony hibernation sites in Michigan, with some colonies numbering over 50,000 bats.

"Our survey efforts focused on areas where WNS would most likely first appear," said DNR Wildlife Biologist Bill Scullon. "Given the speed with which this devastating disease has spread across the country, we're very pleased to have found no visible signs of WNS in Michigan this season. Unfortunately, all indications are that the disease will eventually arrive here."

The invasive fungus Geomyces destructans that causes WNS is believed to have originated in Europe and has spread to 19 states and four Canadian provinces since the first outbreak site was discovered in eastern New York in 2006. WNS has been confirmed in Ontario, less than 90 miles from the Michigan border, as well as in Ohio and Indiana.

 The US Fish & Wildlife Service estimates that since WNS was first detected in the United States, more than 5.5 million bats from six different species have died from the disease, with the mortality rate nearing 95 percent in some affected sites.

Nine species of bats can be found in Michigan, with cave-dwelling bats, such as little brown bats, big brown bats, tri-colored bats, northern long-eared bats, and the federally-endangered Indiana bats, at the greatest risk of contracting WNS.

Michigan's bat species are insectivores and are a highly-beneficial as a natural insect control mechanism. Bats help to protect agricultural crops and forests from damage done by insects such as corn ear worms and gypsy moths, and also reduce the threat of insect-borne diseases such as West Nile virus.

The economic benefit of a healthy bat population in Michigan has been estimated at $508 million annually, and more than $23 billion nationwide.