In late January several hundred bats were found dead near the main entrance of the Vermilion- Soudan Underground Mine State Park by Minnesota Department of Natural Resources (DNR) employees.
When the bats were tested by the United States Geological Survey National Wildlife Health Center, it was determined they had suffered from white-nose syndrome (WNS), a disease that attacks and kills bats that have been hibernating.
An invasive fungus from Europe, WNS was discovered in New York in 2007, and since then has spread to 30 states, killing more than 5 million bats.
The disease causes fuzzy white growths on the noses and faces of the bats, and the fungus eats its way into their wings. Sick bats awaken from hibernation. It is believed they fly out into the cold and die from exposure or from starvation when no bugs can be found.
DNR employees first discovered WNS at the Soudan site in 2013, and they have kept a watchful eye for its expected return.
Minnesota has four bat species that hibernate in the winter. The most affected bats seem to be the little brown bat and the northern long-eared bat. The northern long-eared bat (NLEB) has been placed on the endangered species list as threatened by the U.S. Fish and Wildlife Service (FWS), and last year an interim rule was implemented to protect the NLEB bat from logging and construction operations.
In January 2016, the FWS finalized its rule on the northern long-eared bat, which prohibits timber harvest within 150 feet of “known, occupied maternity roost trees from June 1 to July 31” and prohibits logging within a quarter mile of a known hibernacula (winter den) year-round. As of June 2015, the state had identified 25 known hibernacula and 163 roost trees in Minnesota. While Lake County was identified as having two roost trees and one hibernacula, Cook County was found to have neither.
If the northern long-eared bat continues to decline and is placed on the endangered species list the current rule will no longer apply, and restrictions on activities such as logging will be greatly increased in known areas of the bats.
Unhappy with the current rule, four groups, including the Center for Biological Diversity and the Sierra Club have banded together and in February filed a “notice of intent to sue” the FWS, claiming the rule doesn’t protect the bats habitat and that the bat should have been placed on the endangered species list. The groups have given the FWS until mid-April to correct the rule or it will file a claim in federal court.
As for the Vermilion-Soudan underground mine, it will remain open in the summer, but precautions will be made to keep people from spreading the fungus. WNS doesn’t hurt people, but people have been known to carry it from place to place on their clothing and shoes.
Meanwhile researchers have found a treatment based on a bacterium that inhibits the growth of the fungus. In its second year of trials, wildlife scientists have found that if bats are treated early enough, they can be cured WNS.
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