White-nose syndrome, which has decimated bat colonies in eastern states, has been found at two sites in Minnesota.
Four species of Minnesota bats may be facing a death sentence now that a lethal fungus that decimated their populations in other states has been discovered at two of their largest hibernating sites here.
The disease that results — white-nose syndrome — has not been detected yet in Minnesota, but the underlying fungus has been discovered on four bats in two locations — Forestville/Mystery Cave State Park and Soudan Underground Mine State Park.
The discovery is an early signal of a disease that has wiped out as many as 90 percent of bats in affected colonies in eastern states, which could deal a huge blow to Minnesota’s agricultural economy.
Bats, which can eat half their body weight in insects each night, save Minnesota farmers an estimated $1.4 billion annually in pest control, officials said. They also play a critical role in pollinating many crops and other plants.
The disease is almost impossible to contain once it takes hold, researchers said Friday at a news conference organized by the Minnesota Department of Natural Resources (DNR).
White-nose syndrome does not pose a threat to humans, pets, livestock or other wildlife, but it is devastating to the four species of bats in Minnesota that hibernate during the winter in caves and abandoned mines.
Three other species that migrate every year are not known to be affected.
First documented in New York in 2007, the disease has spread rapidly across the eastern United States and Canada, and the fungus has been detected as far west as Oklahoma.
Bats with the disease, characterized by white growths on their noses and lesions on their wings, exhibit uncharacteristic behavior during cold winter months, including flying outside during the day and clustering near the entrances of their caves.
Winifred Frick, a bat researcher from the University of California, Santa Cruz, said that, while the disease is little-understood, it causes infected bats to wake up too often in the winter. That depletes their hibernation energy stores, and they starve before spring arrives.
The disease has killed more than 5.7 million bats in eastern North America. In some colonies, or hibernacula, 90 to 100 percent of bats have died.
Hard to stop
State and federal officials said Friday that, though research is underway, there is little they can do to stop the spread of the disease or treat infected bat colonies.
Bats spread the fungus from cave to cave, and they range up to 250 miles.
Once the fungus becomes established in a site, then, just like human fungal diseases, it’s extremely difficult to eliminate.
The only practical precaution for now is to reduce the risk of humans carrying it from cave to cave, said Jeremy Coleman of the U.S. Fish and Wildlife Service.
In Arkansas, caves have been closed to spelunkers. But in Minnesota, the two affected sites are extremely popular tour destinations for state park visitors.