Bats are present in Chicago, living within the city’s diverse urban ecosystem. These nocturnal mammals contribute to the local environment.
Bat Species and Their Chicago Homes
Chicago hosts several bat species, with the Big Brown Bat (Eptesicus fuscus) being one of the most common urban dwellers. These adaptable bats often roost in structures like older buildings, attics, barns, bridges, and tree cavities. Big Brown Bats are relatively large, measuring two and a half to three inches long with a wingspan of approximately 13 inches, and have shiny brown fur. They withstand colder temperatures better than some other bat species, allowing them to hibernate in a wider range of locations, including buildings.
The Little Brown Bat (Myotis lucifugus) is recognized by its small size, dark brown fur, and long ears. These bats often roost in buildings or trees during the day, especially near water sources like the Chicago River, where insects are plentiful. They form maternity colonies in warm sites such as attics or bat houses during the summer. Some migrate south or hibernate in caves and abandoned mines during winter. Little Brown Bat populations have faced severe declines due to white-nose syndrome, a fungal disease.
Eastern Red Bats (Lasiurus borealis) are recognized by their distinctive rusty or brick-red fur. These tree-dwelling bats often roost alone among foliage in deciduous or coniferous trees, where their coloration helps them camouflage. While primarily forest dwellers, they are also found in urban areas and may occasionally use attics. Eastern Red Bats migrate to warmer southern regions for winter, though some may hibernate on the forest floor.
The Hoary Bat (Lasiurus cinereus), Chicago’s largest bat species, features brown-and-gray mottled fur that provides camouflage in tree foliage. Hoary Bats are solitary and prefer forested areas, though they are also found in tree-covered residential zones and parks. They spend their days hanging upside down, blending in with leaves, and are not typically found within city structures.
Living Alongside Chicago’s Bats
Bats consume many insects, aiding natural pest control in Chicago’s ecosystem. A single brown bat can eat hundreds of insects in an hour, including mosquitoes and agricultural pests. This natural regulation of insect populations can reduce the need for chemical pesticides and improve environmental health.
If a bat is found inside a home, never handle it with bare hands. Bats can carry rabies, a rare but serious disease, and a bite may not always be noticeable due to their small teeth. If a bat is found in a room with a sleeping person, an unattended child, or if physical contact is suspected, the bat should be safely captured and submitted for rabies testing. Chicago Animal Care and Control can be contacted by calling 311 for assistance.
Residents can support bat populations through conservation efforts. Providing bat houses offers suitable roosting and maternity sites, especially for species like the Little Brown Bat and Big Brown Bat. These structures, often placed near water sources, can accommodate large colonies and help maintain local bat numbers. Preserving natural habitats, such as forested areas and green spaces, also benefits bats by ensuring access to food sources and roosting locations. Community science projects, like the Bat Tracker program, involve volunteers in monitoring bat activity to gather data on their distribution and behavior in urban environments.