The Bats of Chicago

For the last couple years, Lincoln Park Zoo’s Urban Wildlife Institute has spent some time listening to the skies. Because of this data, we now have a pretty good idea of who is flying around at night, chomping up all of the nighttime insects, from moths to mosquitoes.

Now that the weather is turning cooler, most of our bat friends have travelled to their wintering grounds, be them local caves or warmer spots down south. But with Halloween around the corner, it’s time we became better acquainted with our nighttime neighbours. And while these animals might seem particularly spooky this time of year, don’t let their haunting reputation fool you: bats are an essential part of our ecosystem, even in cities!

Of the eight species flying around Chicago, here are five of the usual suspects we see and hear at night.

Big Brown Bats

Creative Commons picture of a hibernating big brown bat. Photo by Ann Froschauer/USFWS

Creative Commons picture of a hibernating big brown bat. Photo by Ann Froschauer/USFWS.

They’re one of the most common city-dwellers. Females of this species can live in groups of 60 or more individuals. They raise their pups together in these maternity colonies and come back to the same group year after year.

Bats are very long lived for their size, often reaching 15 years of age. Because of this, some research suggests that big brown bats might have “friends” within their colonies, and these friendships can last for years! Unfortunately, big brown bat populations have suffered in recent years due to white-nose syndrome.

Eastern Red Bat

An eastern red bat in Indiana. Photo by John Farabaugh.

An eastern red bat in Indiana. Photo by John Farabaugh.

The most brightly colored of our local bat community, this species has beautiful red fur. They spend their winters in the southern United States and have been known to hibernate on the forest floor among the fallen leaves. Like most bats, this species has one or two pups every year.

Hoary Bat

Creative Commons picture of a hoary bat. Photo by jumpingspider.

Creative Commons picture of a hoary bat. Photo by jumpingspider.

The biggest member of our bat community, but it weighs only 35 grams, the equivalent of about 35 pennies! They have a wingspan of about 1.5 feet. This bat is named for the grayish-white sheen of its fur. They live solitarily in the treetops during the summer and are generally not known to be found in cities. Despite this, we regularly hear them flying around the zoo at night.

Northern Long-Eared Bat

Creative Commons picture of a northern long-eared bat. Photo by Al Hicks/NYDEC.

Creative Commons picture of a northern long-eared bat. Photo by Al Hicks/NYDEC.

Another bat named for its appearance, this small bat has relatively large ears, necessary for hearing the echoes as it navigates through cluttered forests. We have heard this bat flying around close to forest preserves, but they completely avoid the downtown area. Tragically, this species is also suffering large population losses (up to 99 percent declines in some areas) due to white-nose syndrome. Because of this, northern long-eared bats are under consideration to be included on the Endangered Species List by the U.S. Fish and Wildlife Service

Tri-Colored Bat

Creative Commons picture of a tri-colored bat. Photo by David J. Thomas.

Creative Commons picture of a tri-colored bat. Photo by David J. Thomas.

This is our smallest member of the Chicago bat community, weighing only 8 grams (or 8 pennies!). This species is found across eastern North America and has been tragically affected by white-nose syndrome. Some populations have suffered declines of up to 95 percent. This species spends winter in caves and mines near their summer grounds, where they hibernate until the temperatures warm up in spring.

Julia Kilgour

Julia Kilgour, M.S., is an adjunct scientist with Lincoln Park Zoo's Urban Wildlife Institute. She's looking for your help to find large bat colonies in the area to study! Send your bat photos, stories and tips to batsignal@lpzoo.org.

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