Northern Exposure

This past winter, white-nose syndrome was confirmed in wild bat populations in southern Illinois. The fatal disease, first discovered in New York State in 2006, is caused by a fungus that infects hibernating bats. It has rapidly spread across the United States and Canada, expanding its range every year and resulting in the loss of more than 6 million bats so far. As a researcher in the zoo’s Urban Wildlife Institute (UWI), I participated in a white-nose syndrome survey at an abandoned mine in northern Illinois at the end of March. I met with scientists from the University of California Santa Cruz and the Illinois Department of Natural Resources.

Hibernating little brown bats infected by white-nose syndrome cluster in a ceiling crevice inside an abandoned mine in northern Illinois. (Photo by Joseph Hoyt.)

After gearing up in Tyvek suits (to prevent disease transmission between caves), latex gloves and helmets, we crawled in the entrance. The walls were speckled with numbers and letters, codes indicating the different branches and networks of the cave. We turned on our headlamps and spoke only in hushed whispers to minimize our impact on the animals.

Soon we could see big brown bats hanging delicately from the ceiling, deep in their cool winter slumber. As we progressed through the tunnels, climbing over rocks and around pools of water, the bats became more and more numerous. Dozens of little brown bats were cuddled together, many with visible white on their muzzles—the telltale sign of the aptly named white-nose syndrome infection. Northern long-eared bats were scattered throughout the mine, some also showing signs of the fungus on their faces and bodies.

Occasionally, we’d spot the small tricolored bats, their bright orange bodies contrasting against the dull gray walls of the mine. While some researchers were counting and identifying species, others were taking swabs from the walls and off the bats themselves, trying to get more information about this deadly disease.

Seeing these animals in their winter habitat was like peering into a secret land: while bats are commonly seen flying overhead at dusk in summertime, their winter world is completely unknown to most of us. Tragically, observing bats during the winter months is likely going to become a rare event as white-nose syndrome continues to expand across the continent.

Urban Wildlife Institute researcher Julia Kilgour prepares to slip a Tyvek suit over a caving suit before heading into a mine to study native bat colonies. The protective clothing layers help scientists prevent the transmission of white-nose syndrome between caves.

It’s too early to predict exactly how the arrival of this disease is going to affect bats or how their ecosystems may be affected by the loss of a critical species. Many of the bat species most affected by white-nose syndrome, such as big brown bats and northern long-eared bats, play a critical role in controlling pests—a major benefit to the agricultural industry.

Close observation of populations is essential to understanding these impacts. The UWI and I will continue to passively monitor bat populations by recording their echolocation calls in the summer to better understand how white-nose syndrome is affecting these important, local species.

Julia Kilgour is a project coordinator in Lincoln Park Zoo’s Urban Wildlife Institute.


Thanks for the local update on this topic. I'm really bummed to hear that this fungus and disease has moved into our region. Is there any information from research yet on how to combat this? Is this a fungus that has been in our region a very long time, or is it a recent arrival?

Mary, white-nose syndrome first appeared in New York in 2006. It's been moving steadily west since then, and it was spotted in Illinois for the first time this March, as President and CEO Kevin Bell shared at the time. Unfortunately, there isn't currently a way to treat the disease, although research continues.

So from the pictures, am I to assume that white nose is now in Northern IL colonies also? Were these the ones in the limestone mines outside of Ottawa?

Yes, Dale, the infected bats were confirmed in the limestone mines in LaSalle County. Unfortunately, WNS was also confirmed in Monroe, Harden and Pope counties.

Loss of bat population

We have seen a complete disappearance in bat population in our backyard located in rural Henry County, IL with a MASSIVE increase in mosquitoes. Would WNS be attributed to this? What can we do to attract the bats back to our property in addition to building a bat house? I know they are the best resource for insect control, I just want to be sure we are doing everything we can to be proactive.

Re: Loss of Bat Population

Sheri, we passed your question by Wildlife Research Coordinator Pat Wolff, and he says, "I’m sorry to hear about the disappearance of your bats, but I appreciate your enthusiasm! White-nose syndrome likely occurs in your area, so it’s possible that bats are dying off as a result. However, I wouldn’t attribute the observed increase in mosquitos solely to a decrease in bats. We’ve had an unusually wet spring (wettest June in history) and summer in Illinois, which can lead to particularly bad mosquito outbreaks. Also, bats are opportunistic feeders and don’t focus just on mosquitos; they like to eat moths, beetles, flies, crickets, gnats and other insects, too. The increase in mosquitoes is likely due to a combination of factors, with the decrease in bats being just one among them.
You’re absolutely right about bats being great pest controllers, and they also save the agricultural industry billions of dollars each year. The best thing you can do is make sure your bat house is properly designed and positioned. It’s possible that your bats didn’t come back this year if other residents moved in (like wasps or bees) or if the house is damaged (making the internal temperature unsuitable). Try to place the bat house at least 15 feet high and facing southeast, where it will receive 6-8 hours of direct sunlight. You could also try planting a night garden to attract insects for the bats to eat. Otherwise, just try to stay patient. Perhaps the bats didn’t come back for a different reason, but they’ll be back next year."

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