Tiny Bats Hibernate in Historic Keweenaw Mine Shafts

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As winter settles in, a small but mighty creature finds refuge in the historic mine shafts of Michigan's Keweenaw Peninsula. The silver-haired bat, a common species across America, is one of four bat species that hibernate in the caves and abandoned mines of this unique region, which serves as a critical overwintering habitat for seven of Michigan's nine bat species.

Why it matters

The Keweenaw Peninsula is a hotspot for bat activity, and these hibernating bats play a vital role in controlling insect populations, saving U.S. farmers billions of dollars annually in reduced pesticide costs. Understanding where bats roost is essential for effective conservation efforts.

The details

The silver-haired bat, measuring around 4 inches in length and weighing about half an ounce, is a medium-sized species that primarily feeds on soft-bodied insects like flies, mosquitoes, and termites. A single bat can consume thousands of insects in a single night, contributing significantly to Michigan's ecosystem and economy. The Michigan Bat Roost Monitoring Program is working to improve knowledge of bat roosts across the state to guide conservation efforts.

• As winter grips Michigan, bats seek shelter in the cool, stable environment of the abandoned mine shafts.
• The silver-haired bat is a common sight in forested areas across America, but it hibernates in the caves and abandoned mines of the Keweenaw Peninsula.

What’s next

The Michigan Bat Roost Monitoring Program continues to collect data on bat roosts across the state to inform conservation efforts.