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.

Silver-Haired Bat

Creative Commons picture of a silver-haired bat. Photo by LassenNPS.

Creative Commons picture of a silver-haired bat, cropped and retouched. Photo by LassenNPS.

Another bat named for its appearance, silver-haired bats are medium sized and appear almost black with very subtle silver-tipped fur. As a tree-roosting bat, silver-haired bats are solitary, roosting alone in tree cavities, beneath bark or among leaves. We have detected silver-haired bats throughout the Chicago area, including downtown.

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



We see bats come out every evening. Today I was bird watching and thought I found bats sleeping in tree tops. I live in Villa Park, IL. I'm curious if it is possible those are really bats up there? What kind would you expect them to be?

Re: Bats

Great question, Gail! We passed it by Urban Wildlife Institute Research Technician Patrick Wolff, and he says, "They definitely could be bats!  There are several species in your area that might roost in trees during summer.  However, the eastern red bat and hoary bat would be most likely to be seen among the foliage.  Other species, such as the big brown bat, little brown bat, silver-haired bat, and tricolored bat prefer to hide under loose bark or in hollows."


Last night (around 10:30) a bat flew into our house through our back door, which I'd opened for a few seconds to put something onto our back porch. I realized it was in the house when I saw it swooping around our kitchen, close to the ceiling. Poor thing was trying to find a way out; we opened the back door again, and after a few tries, out it went into the night.

I've been trying to figure out what kind of bat it was, but nothing I see online matches it. My husband and I both got a close look at it when it landed on our kitchen floor a few times. Its body was quite small, about three inches long. Its wingspan was about six inches. Couldn't get a good look at its face. But its coat was black; no silver or any other color, not brown, just black. It was actually quite beautiful. Any idea of what species it could've been? I wish I'd had the presence of mind to take a photo of it, but we were concentrating on getting it out of the house unharmed.

By the way, we're just north of Loyola University, Rogers Park, a few buildings from the lake. There are big lights on at night over Hartigan Beach, which of course attract bugs, a big draw for bats!

Re: Bats

Zephyr, we passed your question on to Urban Wildlife Ecologist Liza Watson Lehrer, and she responds, "Thank you for the sighting! I suspect it was a small silver-haired bat. They can appear very dark, and the silver tips of the hair might not be obvious unless in direct light. We know them to occur in the city and it could have been moving along the lakefront. Sounds like an exciting evening, but we're glad to hear it came and went safely!"

batty for bats

i discovered a bat hanging from my deck feeding on bugs at the porch light. i live in lincoln square. the bat was large and startled me. i was curious what type of bat it might have been.

Re: Batty for Bats

Kristi, Urban Wildlife Ecologist Liza Watson Lehrer replies, "Thanks for the sighting! Given that you say it was large, it was likely a big brown bat or a hoary bat. Big browns are more uniformly brown in coloration, whereas hoary bats have mottled gray/brown fur. Both species tend to do well in urban areas, taking advantage of old buildings and attics as roosting spots and foraging on insects, as you describe."

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