White-nose syndrome (WNS) is a devastating disease responsible for the deaths of nearly 7 million bats in eastern North America. Since it was first observed in a New York cave during winter 2006/2007, WNS has spread swiftly to 19 states and 4 Canadian provinces causing massive die-offs of hibernating bats. All four bat species that hibernate in Minnesota are vulnerable to this disease—Little Brown Myotis (Myotis lucifugus), Northern Long-eared Myotis (Myotis septentrionalis), Tri-colored Bat (Perimyotis subflavus), and Big Brown Bat (Eptesicus fuscus).
Bats are a critical part of Minnesota's ecosystems, consuming vast numbers of insect pests that spread disease and damage crops and forests. During summer, a nursing female bat may consume up to it body weight in insects each night. The value of bats to Minnesota agriculture has been estimated at $1.4 billion per year.
Updated September 3, 2014. Re-examination of the 2010 specimen from Oklahoma has led to the removal of that state from the list of suspected or confirmed WNS states and provinces. Map design by Tom Klein/MNDNR. Map features provided by Cal Butchkoski and Lindsey Heffernan, Pennsylvania Fish and Game Commission.
The Minnesota Department of Natural Resources (MNDNR) is the lead agency for WNS response in Minnesota. Staff from the Minnesota Biological Survey, Parks and Trails, and Nongame Wildlife monitor the health of Minnesota's bats. We collaborate with other state and local organizations, academic researchers, and with federal, tribal, and non-government agencies across North America to better understand WNS and find ways to limit its spread.
Recently DNR staff assisted cavers visiting Forestville/Mystery Cave State Park with implementing WNS decontamination procedures.
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What is white-nose syndrome?
White-nose syndrome (WNS) is a disease that is killing hibernating bats in eastern North America. Nearly 7 million bats have died as a result of the disease, so far.
Named for the white fungus that was observed on noses of the first infected bats, it also affects other body parts. A newly discovered fungus, Pseudogymnoascus destructans, (formerly known as Geomyces destructans), has been demonstrated to cause WNS in bats. The fungus thrives in cold, humid conditions characteristic of the caves and mines that bats use to hibernate.
WNS was first documented New York in the winter of 2006-07. The disease continues to spread westward as shown in the map above.
How is WNS transmitted?
Scientists believe that WNS is transmitted primarily from bat to bat. Humans and other animals visiting infected caves and mines may inadvertently carry the fungus to unaffected caves. The fungus can remain in a cave after all the bats have died.
Is WNS dangerous to humans?
No. Bats appear to be the only animals that are susceptible to this disease.
What are signs of WNS?
Bats appear to die from WNS primarily during winter, due to starvation, physiological shock or freezing. During winter months, observable signs of WNS may include:
white fungus on the bat's muzzle and other hairless parts of the body, such as wings and tail
bats active outside during the day when temperatures are below freezing
bats clustered at the entrance of hibernacula
dead or dying bats on the ground or on buildings and trees
Note: The WNS fungus does not grow on bats during the warm weather months when bats are active. Also, other white fungi may grow on dead bats that are not associated with WNS.
What should you do if you find dead or dying bats, or if you observe bats with signs of WNS?
Contact the Minnesota Department of Natural Resources.
- File Bat Observation Report, or
- Send an email to MBS eReport , or
- Leave a toll-free phone message to the MBS Report Line: 1-888-345-1730
Photographs of the bat and details about its behavior or where and when it was found are very helpful.
Use caution when handling bats: Never handle live bats without gloves. If a person or pet has been exposed to a bite, scratch, or saliva from a live or dead bat, contact the local public health department for further guidance.
What species of bats are affected?
Seven bat species reside in Minnesota. Four hibernate in caves and mines and three migrate out of the state during winter. All four of the hibernating species have been shown to be affected by WNS in other states. These are Little Brown Myotis (Myotis lucifugus), Northern Long-eared Myotis (Myotis septentrionalis), Tricolored Bat (Perimyotis subflavus), and Big Brown Bat (Eptesicus fuscus).