A Year of Native Animals: Little Brown Bat

In 2026, Friends of the Chicago River invited people across the Chicago-Calumet River system to make Wild River Resolutions, a yearlong reminder to discover, celebrate, and protect the wildlife that depends on a healthy river. Throughout the year, we are highlighting 12 native animals, one each month, that call the 156-mile river system home.

Designed to both educate and inspire, Wild River Resolutions connects people to the species living in and along the river while spotlighting simple, everyday actions that support a healthy, biodiverse, and accessible river system for all people, water, and wildlife.

June – Little brown bat (Myotis lucifugus)

Found in many parts of North America, including most of the contiguous U.S. and parts of Mexico, little brown bats were once common in the Chicago-Calumet River watershed. They have large, furry toes and dark brown fur on their back. Incredible fliers who use echolocation to hunt their prey of as many as 1,000 insects a night, little brown bats tend to roost in caves in summer, but can also be found in human made structures, trees, under rocks, and in piles of wood. These bats hibernate in caves, tunnels, and mines over the winter.

They mate in the fall, after which females give birth to a single pup in the spring after a delayed gestation period. This bat’s population has been decimated by white-nose syndrome, a fungal disease and they get killed by wind turbines at a significant rate. As a result, their numbers have been dwindling and local researchers only record a few little brown bat calls each year. Friends has installed bat maternity colonies to augment reproductive habitat.

Learn more about bat species of the Chicago-Calumet River system on Friends’ Inside, Out & About podcast.