SHOREWOOD – The big brown bats that roost inside the Shorewood Grove Shelter in Hammel Woods forest preserve during the summer have for decades startled people, periodically flying in and out.
But Will County Forest Preserve officials say it is humans who disturb the bats’ daytime slumber with noise and smoke from picnic barbecues at the 80-year-old shelter.
“That’s why they sometimes fly out,” said Juanita Armstrong-Ullberg, forest preserve natural resource land manager.
Now forest preserve officials hope the bats will move out of the shelter into a new “bat condo” specially tailored for the needs of the animals.
The district hired Pennsylvania-based Bat Conservation and Management Inc. to construct the bat condo just north of the shelter.
Armstrong-Ullberg said the forest preserve wants to keep the bats around, noting they serve a useful purpose.
“Bats are nature’s insect repellent. They’re very important,” she said. The forest preserve just wants them to find a new home nearby.
“We want to discourage them from coming back to the shelter,” Armstrong-Ullberg said. “The condo will be warmer, wind-free and provides a base in case young pups, the babies, fall.”
The condo, which sits about 12 feet above ground, looks like a giant wooden birdhouse from the outside. Inside, it contains several rows of inch-wide crevices, which bat consultant Janet Tyburec said creates optimal conditions for socializing and sleeping during summer days.
The wooden crevices are roughened to give bats more grip. And the condo, which can hold up to 250 big brown bats, is cured to keep in more heat.
“Bats are unique in that they like it really hot in the summer, and really cold in the winter,” Tyburec said. That’s why states around Lake Michigan are popular nesting grounds.
Armstrong-Ullberg said the forest preserve is a habitat for eight of the nine species of bats found in the Midwest. But only big brown and little brown bats roost inside the picnic shelter.
The condo is meant to replace the shelter as a summer home for female, young male and baby bats. But it may take a year or two before most bats recognize the condo as a suitable home. The early fall construction will give time for the bats to find the condo.
The condo is located in a field north of the shelter. But people don’t need to worry about attacks from bats, especially because forest preserve officials say bats are more active at night.
“It’s better than bats roosting inside the shelter, where people are eating and socializing,” Armstrong-Ullberg said.
The condo cost the forest preserve $3,500, while installation cost $300. Part of the project was paid for by a Wildlife Preservation Grant from the Illinois Department of Natural Resources.
Armstrong-Ullberg said she plans to install more natural prairie grass and plants around the condo. There will also be a small educational kiosk with bat facts.
“There is still so much we don’t know about bats,” she said, pointing out that research on bats didn’t really start until the 1970s.
Armstrong-Ullberg, who is thought of as “Bat Girl” among forest preserve staff, believes the big brown bats in Hammel Woods migrate to Wisconsin during the winter to hibernate after breeding in the fall.
The forest preserve is also installing an iButton in the condo, which will measure temperature, humidity and other conditions so officials can research the bat colony in a nonintrusive manner.
“One 20-ounce bat can eat its own body weight in mosquitoes and moths,” Armstrong-Ullberg said. That amounts to more than 3,000 insects in one night.
“These are good creatures,” she said. “The condo will help.”