Bats Active in Winter?

Bats Active in Winter?

Licia Johnson, Naturalist

We’ve had a few calls in December from folks seeing bats flying around their houses. One was at the local library, one was caught in a mouse trap in the basement of a Stevens Point home, and one was sleeping behind a curtain in my living room!  Shouldn’t the bats be gone, either hibernating in caves or migrating? 

I too was curious about these sightings and I’ve since found some information you might find interesting. One bat species -- Big Browns (Eptesicus fuscus) -- have adapted to living year-round in buildings in the northern half of the United States and Canada and occasionally awake (as do many bats to drink or urinate). If you live in this region and find an active bat in your home or yard during winter, it is almost likely a Big Brown bat. Unlike most other North American cave-dwelling bats, Big Browns can survive temperatures well below freezing (many others need temps between 32-49degrees), and are therefore able to hibernate in cold attics and wall spaces. Check out this ARTICLE by Merlin Tuttle from Bat Conservation International for more information on bat hibernation & migration. 

The photos here are from a ‘Bats of Wisconsin' program hosted at the Mercer Public Library as part of the Brown Bag lecture series.  This bat (the one I found in my home) was taken to Wild Instincts Rehabilitation Center in Rhinelander to be put into hibernation the next day.  If you are interested in bats or in becoming a part of our Acoustic Bat Monitoring crew, check out our winter/spring guide or visit our event calendar online for programs and trainings this spring! 

Photos by Teresa Schmidt, Mercer Public Library