Once common Minnesota bat declared endangered due to fungal infestation

The northern long-eared bat, which was once common in Northland forests but is rapidly dying off due to an invasive fungus, was officially listed as an endangered species by the US Fish and Wildlife Service on Tuesday.

The Biden administration made the move in a last-ditch effort to save bats that winter in caves and abandoned mines where they spread deadly white-nose syndrome among themselves, like at the Soudan Underground Mine near Tower, Minnesota.

The disease causes the bats to overheat, become active when they should be hibernating, and eventually starve and die. Almost always fatal, the fungus has wiped out entire hibernacula (winter roosts) and millions of bats, including an estimated 96% of all northern long-eared bats, since its discovery in New York in 2006.

A bat at Soudan Mine in northern Minnesota is showing signs of white-nose syndrome, a disease that is harmful to overwintering bats and is usually fatal.  (Courtesy of Christine Salomon / University of Minnesota)
A bat at Soudan Mine in northern Minnesota is showing signs of white-nose syndrome, a disease that is harmful to overwintering bats and is usually fatal. (Courtesy of Christine Salomon / University of Minnesota)

The disease originated in Europe, where bats appear unaffected.

The nationwide endangerment status, which will come into effect on January 30, is an upgrade of the protection status that the bat has had since 2015. But wildlife authorities concede there is little they can do other than provide the few remaining northern long-eared bats with good habitat and continue to search for some kind of cure.

At the Soudan mine, where thousands of northern long-eared bats have been sighted each winter when the Minnesota Department of Natural Resources surveyed bats far underground, not a single northern long-eared bat was counted last winter.

“This listing is an alarm bell and a call to action,” Martha Williams, director of the US Fish and Wildlife Service, said in a statement announcing the action. “White-nose syndrome is decimating cave-dwelling bat species like the northern long-eared bat at an unprecedented rate. The service is committed to working with partners on a balanced approach that reduces the impact of disease and protects survivors to allow northern long-eared bat populations to recover.”

The disease has spread to nearly 80% of the geographic range inhabited by northern long-eared bats and is expected to cover the entire range by 2025. Other species stricken by the fungus include the tri-colored bat, which the government planned to list as endangered in September, and the little brown bat.

Restoration efforts are focused on forested areas where the bats roost during the day during the summer, usually in burrows in large, mature trees. And it’s possible that endangered status could affect some logging in states like Superior, Chequamegon, and Chippewa National Forests.

Under the Endangered Species Act, federal agencies must consult with the Fish and Wildlife Service to ensure projects they fund or authorize, such as tree felling, mandated fires, and road construction, do not further endanger the bat. For non-federal landowners, such as the state and counties, acts that could lead to accidental killings might be permitted but require permits.

The agency said it will also work with wind energy companies to reduce the chances of bats hitting turbines. These collisions currently pose a threat to about half of the northern long-eared bat’s range, an area likely to grow as wind energy development expands.

Research into methods to combat white-nose syndrome, including the development of a vaccine, continues. The federal agency had allocated approximately $46 million to the effort, which involves nearly 150 agencies, universities, private groups and Indigenous tribes.

Bats are critical to healthy, functioning natural areas and contribute at least $3 billion to US agriculture annually through pest control and pollination. The northern long-eared bat is found in 37 states in the eastern and northern United States, the District of Columbia and all Canadian provinces from the western Atlantic Seaboard to the southern Northwest Territories and eastern British Columbia.

White-nose syndrome is caused by the growth of a fungus that sometimes looks like white fuzz on the snouts and wings of bats. The fungus thrives in cold, dark, damp places and infects bats during hibernation. Affected bats wake up more frequently, often leading to dehydration and starvation before spring arrives.

Bats are the only wildlife species known to be affected by white-nose syndrome, confirmed in 38 states, including Minnesota and Wisconsin, and eight Canadian provinces.

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