While you may think bats are rodents, you would be wrong. Wisconsin’s only flying mammal is more closely related to primates and are in an order entirely on their own Chiroptera. With 1,000 species of bats around the world, they make up 25% of all mammals. Bats are a vital part of Wisconsin’s natural ecosystems. Just like the birds, butterflies, and bees you may be trying to attract with your landscaping, bats are pollinators and disperse seeds. Bats also play an important part in protecting people from insect born diseases like West Nile by consuming insects like mosquitos. A singular bat can consume up to 1,000 mosquito sized insects in an hour. Bats also consume many agricultural pests that can cost the crops of farmers and foresters alike. It has been estimated that the bat population in Wisconsin has saved farmers $658 million in pest control services every year.

Wisconsin has eight species of native bats, all of which are insectivorous and use echolocation to navigate and capture prey. They can be split into two categories; tree bats and cave bats. Tree bats include the Silver-haired bat, Hoary bat, Eastern red bat, and Evening bat. The tree bat populations in Wisconsin are not currently endangered or threatened. The other category, cave bats, are not so lucky. All four species of cave bat are currently listed as threatened by Wisconsin’s Natural Heritage List; The little brown bat, the big brown bat, the tricolored bat, and the Northern long-eared bat.

Little Brown Bat (Myotis lucifugus)







Big Brown Bat (Eptesicus fuscus)







Tricolored Bat (Perimyotis subflavus)






Northern Long-eared Bat (Myotis septentrionalis)








The reason for their threatened status can be linked to their homes, cave dwelling bat populations have been in rapid decline due to a devastating fungal disease that causes mortality called White-nose Syndrome. The fungus (Pseudogymnoascus destructans) grows in the cool conditions of Wisconsin’s caves and mines and grows on the faces and wings of bats in torpor. The syndrome has a fatality rate of 95%. Not much is known about the mechanisms of the syndrome though it has been shown to prematurely wake bats from their winter torpor and burn crucial fat reserves causing starvation and death in the winter months. Since it was discovered in North America in 2006, white-nose syndrome has caused a nearly 100% decline in the numbers of the bat population. White-nose syndrome is a threat to all four of Wisconsin’s native cave dwelling bat species.


The only way to help prevent the spread of white-nose syndrome is to clean off your boots, clothes, and equipment after entering caves or mines as spores can survive on clothing for months unknowingly being transported between caves, counties, states, and countries by nature enthusiasts. The below image is from the most recent map showing the spread of white-nose syndrome created by the White-nose Syndrome Response Team a group of biologists, researchers, land managers and naturalists across North America that are united in protecting America’s native bat populations under a national plan coordinated by the U.S. Fish and Wildlife Service.









If you find a dead bat and suspect it may be white-nose syndrome or another disease, you should report it to the DNR bat program to help them track trends in the decline of the population. Never handle a sick or dead wild animal without the proper instruction. https://wiatri.net/Inventory/Bats/Report/

If you would like to help conserve Wisconsin’s dwindling bat population, please get in touch with the DNR to take part in one of their citizen science based monitoring programs. Acoustic monitoring equipment is available to volunteers and allows people to record the ultrasonic range of sounds created by bats using echolocation. The monitoring application is able to take the recorded sounds and determine the species of bat and log the flight path and location for use in population statistics. Acoustic surveys can take place while walking on land, boating, or driving, and it’s a great Scout or 4H activity for kids. You can also take part in the roost monitoring programs. Little brown bats and big brown bats both form large colonies, roost surveys include monitoring roosts to count the number of bats coming and going from their roost around sunset. You can also report bat roosts to the DNR by emailing DNRbats@Wisconsin.gov. You can find more information about bat monitoring and the DNR’s volunteer program HERE.

Dani DeCloux – Environmental Operations Manager