Fungus Causing Deaths of Millions of Bats Now Found in Minnesota

Minnesota wildlife officials announced today that the fungus that causes white-nose syndrome -- a deadly disease that has killed millions of bats in North America -- has been found on bats in two state parks. The announcement comes less than two weeks after Arkansas wildlife officials reported that the same fungus had been found by scientists in two locations in that state. White-nose syndrome has killed nearly 7 million North American bats since 2006, and has so far spread to 22 eastern, Midwestern and southern states and five eastern Canadian provinces. Four other states, including Minnesota, report the presence of the fungus on bats that have not yet shown signs of sickness.

"As this fungus keeps marching farther and farther west, it's clear every hibernating bat species between the Mississippi River and the Pacific Ocean is at serious risk," said Mollie Matteson, a bat specialist with the Center for Biological Diversity. "Yet just 10 days ago, the federal government weakened its protection for bats on western public lands, when it should be doing everything to give bats a fighting chance."

Scientists leading a national study of the spread of white-nose syndrome detected the fungus at Forestville/Mystery Cave State Park in southeast Minnesota and at Soudan Underground Mine State Park in the northeast corner of the state. Samples were taken in 2012 and 2013. Four bats recently tested positive for the presence of the pathogen that causes the disease. More sensitive tests are increasingly allowing researchers to confirm the fungus at an earlier stage than was previously possible. In the past, biologists could only detect the fungus when there were visible signs of it growing on bat noses and wings.

"This disease is taking a terrible toll on America's bats, so it's deeply alarming to see it show up in more and more places," Matteson said.

Bats are the primary vector of the fungus, which attacks them as they hibernate in winter. But biologists have documented that people can also transport the fungus on their clothing, shoes or equipment. The fungus appears to have originated in Europe, where scientists have found it on bats in caves throughout the continent. However, European bats do not fall ill from the fungus. Most scientists believe that people are responsible for inadvertently transporting the fungus from a European cave to the site where the bat disease was first discovered in 2006, at a cave connected to a popular tourist cave in upstate New York.

Land-management officials have closed caves in much of the eastern and southern United States, as well as in a few locations in the West, as a precautionary measure to help slow the human-facilitated spread of the disease. However, thousands of caves on western public lands remain open to recreational use. Earlier this month, the U.S. Forest Service loosened restrictions on recreational cave access in Colorado, Wyoming Kansas, and South Dakota, reversing a three-year closure order aimed at reducing the risk of human transmission of the bat disease into the West.

Background
White-nose syndrome has been called the worst wildlife health crisis in recent memory, and has caused mortality rates among bats ranging up to 100 percent in affected caves. There is no known cure for the disease, which has afflicted seven bat species so far and has pushed several of them to the brink of regional extinction. Many leading bat biologists have emphasized precautionary measures, such as closures and site-specific caving gear requirements, as the best management response.

In 2010, Wisconsin instituted a number of policies aimed at keeping the white-nose fungus out of the state for as long as possible. These measures included listing several bat species as endangered under state law and declaring the importation of the white-nose fungus illegal. The policy also encouraged closures of caves to recreational use. Wisconsin is still officially fungus- and disease-free. However, that status is unlikely to last long, with two of its neighbors -- Iowa as well as Minnesota -- reporting the fungus's presence, and with the disease having been confirmed this past winter in Illinois.

Scientists have estimated the economic value of insect-eating bats to American agriculture at $22 billion annually. Bats also eat tons of insects harmful to forests, and their guano is essential to the survival of extremely rare cave organisms, such as cave salamanders and fish.