Where do Chicago's bats hang out?

A closer look at urban bat diversity and what threatens it

July 30, 2014

Logan Jaffe and Jennifer Brandel

Rory Keane was ambling around Chicago’s downtown a few years back when he stumbled upon what looked like a piece of fried chicken glistening on the sidewalk. But it didn’t take long for him to be disabused.

“I saw it twitch real quick,” he says. “The next thing I knew, it grew wings and it was flying around my ankles and then right past my face.”

It was a bat, in broad daylight, just doing its bat thing downtown. Soon after, Rory collected himself from fright and submitted these questions to Curious City:

How many bats are in Chicago’s Loop? What are their favorite hangouts?

Spoiler alert: Our experts say we can’t pinpoint exactly how many bats call the Loop home. Nor can we locate particular buildings the critters like, either. (Alas, someone else will have to explore whether the gothic tower atop the Wrigley Building acts a bat-magnet). But experts can say which types of environments Chicago’s bats like to hang out in and how popular those sites are.

The takeaway is that these furry fliers are likely closer than you think. And, beyond that: All this bat activity’s a good sign, given that there’s an ominous threat to their very existence.

Where local bats aren’t

In 2012 researchers at the Lincoln Park Zoo’s Urban Wildlife Institute embarked on a study to measure the Chicago-area bat population. They wanted to learn more about which bat species call Chicago home (or were at least recurring squatters), gauge their numbers and determine their favorite haunts, all with the hopes of keeping close tabs on bat species affected by the fatal spreading disease called “White Nose Syndrome.”

By 2013, the scientists had set up 18 bat detectors in various habitats around Cook and Kane counties: forest preserves, golf courses and at the Lincoln Park Zoo’s Nature Boardwalk. As much as we hate to let Rory down, none of these detectors was in the Loop.

That’s for several reasons.

The first one: Bats probably aren’t hanging out downtown. Liza Lehrer, a research coordinator at UWI, says bats might fly through the Loop looking for food, but likely wouldn’t make a home in urban infrastructures like skyscrapers. But if we were to try to pinpoint a bat hangout in the Loop, Lehrer says, be on the lookout for older, cozier buildings with lots of nooks and crannies.

“They like old churches, barns, things like that — areas with lots of older architecture with attics that are easy to get into through roofs,” Lehrer says. “Maybe the Bucktown, Wicker Park areas, but I’m sure anywhere around the city where they can use those spaces they’re probably using them.”

Lehrer says it’s hard to put a number to how many bats hang out in urban infrastructure. But she wouldn’t be surprised if there were 1,000 or more bats living in older Chicago neighborhoods.

“Maternity colonies can have hundreds of individuals in one colony,” she says. “So it’s very possible there are thousands in the Chicago area for sure.”

The second reason why UWI didn’t place bat detectors in the Loop has to do with sound.

Julia Kilgour, a former UWI bat researcher, says the sheer noisiness of the Loop makes it a bad environment to pick up bat calls, and it’s even noisier for the bats themselves.

If you were sick the day they talked about echolocation in school, here’s how bats navigate the world. Their eyesight isn’t so hot, but their hearing is. Bats send out ultrasonic calls, which bounce off trees, buildings and prey. They listen to these echoes to locate who and what is around them.

Echolocation is not a problem in quiet, rural areas; but in dense, urban areas like the Loop, bats have a harder time pulling it off.

Rory himself was on to that explanation: “I imagine if I’m a chic urban bat and looking for a place to live, the Loop would be accommodating ... but it would be noisy.”

Where the bats are

UWI researchers had plenty of other locations to gather data from; they’ve analyzed thousands, if not millions, of bat calls gathered from forest preserves and golf courses around the Chicago area. Liza Lehrer says she’s counted up to 3,000 calls from one detector in a single night.

“What’s really exciting about what we’ve found so far is we see a lot of bats in Chicago, both in urban and rural areas,” she says. “We actually see more bats using Cook County sites in the height of the summer, but out in rural areas we saw more consistent numbers.”

Another interesting finding? Bats really like golf courses.

“You may not consider that an area for wildlife, but there’s lots of bat diversity in golf course sites,” Lehrer says.

Golf courses aren’t as dense as the city’s forest preserves and typically contain a small body of water, so they appeal more to tree-roosting bats, such as the hoary bat and the eastern pipistrelle.

(To see a breakdown of favorite bat habitats around Chicago, check out our visualization by artist Erik Rodriguez, based on research provided by the UWI).

But the finding Lehrer says she’s most excited about is that all seven species common to Northeastern Illinois have been detected at the Lincoln Park Zoo’s Nature Boardwalk, a mere three miles north of the Loop.

“[Bats are] living right here in Chicago, right in the middle of the city, right here at the zoo,” Lehrer says. “We’re fortunate to have an amazing array of green space in the city so they’re able to take advantage of that as much as possible.”

The dreaded white-nose

Finding all seven bat species so close to a dense metropolis is especially exciting, Lehrer says, because several species are directly threatened by white-nose syndrome.

A bat afflicted by the white fungal disease can wake up early during winter hibernation. Affected bats become active right when nature designed them to conserve energy and do as little as possible: when food stores are low and temperatures are dangerous. Lehrer draws an analogy that Chicago-area residents can certainly relate to. “If you think about if you emerged from hibernation during our polar vortex,” she says, “there’d be nothing for you to eat. It’d be very difficult for you to survive if you were a bat. So, thats what’s happening. They emerge from wintering spots and aren’t able to survive or find food.”

Since white-nose syndrome spreads when bats are hibernating in close proximity, Lehrer says, “some caves have found up to 90 to 100 percent mortality.” According to the U.S. Fish and Wildlife service, the disease has killed millions of bats across the U.S. and Canada. There have been confirmed sightings in Illinois, as well as several neighboring states.

The disease is hitting some bat species harder than others. Of the seven species that call the Chicago area home, the big brown bat (Eptesicus fuscus), the little brown bat (Myotis lucifugus), and the tri-colored bat (Perimyotis subflavus) have been susceptible.

The UWI study is one effort to monitor bat populations, health and behavior while scientists find cures for the disease.

So while bats may be on the top of the list of scary creatures for many Chicagoans, the scarier proposition is that there would be no bats left. At least, that’s how Rory Keane feels about it.

“When you come across something really puzzling like WNS … it’s troublesome,” he says. “If it spells the end for bats it’s just one more fixture in the ecosystem that’s going to throw things out of balance for us as we experience it every day.”

He points to a scene most Chicagoans can relate to.  

“If you’re driving down Lake Shore Drive and it’s a clear day and you can see the skyline in front of you,” he says, “you marvel at the success we’ve built up around us. … But could it have all worked out without the contributions of even these tiny, erratically-flying, illogical mammals we call bats?”

Our question comes from: Rory Keane

Chicagoan Rory Keane got us looking into bat habitat a few years after he nearly stomped on one that was hanging out in the Loop. A graduate from Northwestern’s Medill School of Journalism, he’s worked as an English teacher in China and is currently working as a digital marketer in Chicago.

“I guess you could characterize me as a curious person,” he says. “I have a little bit of a curiosity when it comes to travel and seeing the world from a different perspective.”

So, he’s no stranger to new experiences, but he still didn’t expect to get a new perspective from that one, tiny bat in his hometown.

“It was already an incredibly precious encounter given that you would never expect it,” Rory says of the eastern red bat he nearly squashed. “It took a bat to startle me into realizing what was going on around me [in the natural world] on an everyday basis.”

Did we mention Rory also does a fantastic Werner Herzog impression? You gotta listen to his speculations on what life as a Chicago bat is like:

Jennifer Brandel is Curious City's senior producer and Logan Jaffe is Curious City's multimedia producer. Bat and habitat illustrations by Erik Nelson Rodriquez.