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.