The surprising link between protecting bats and the Routes 31 and 47 widening projects in McHenry County

At dusk during northern Illinois summers, it’s not unusual to look up at the early night sky and see bats swooping down to grab a mosquito dinner.

Those are likely big brown bats, Joe Kath said, and he knows bats. As the endangered species program manager at the Illinois Department of Natural Resources, he’s been studying the flying mammals for more than 20 years.

“They are very common and adapt well to using artificial structures like barns and abandoned homes to roost,” Kath said.

Red and hoary bats also are very common in the area.

“If you saw a red or a hoary up close, you would be in awe of their beauty and blown away by how beautiful the fur is and how gorgeous they are,” Kath said.

A total of 13 bat species are found in Illinois, but six of them are state or federally ranked as endangered or threatened.

The northern long-eared bat used to be very common here before a fungal infection found in 2006 in upstate New York spread, decimating the species across the U.S.

“Between 95% and 98% of the total North American population of northern long-eared bats ... no longer exists solely due to white nose syndrome,” Kath said.

Helping those remaining northern long-eared bats survive also is why it was a rough winter for roadside trees in McHenry County.

In December, contractors for the Illinois Department of Transportation began clearing roadside trees along Route 47 in Woodstock. Then, in February, crews started cutting down trees on Route 31 from Crystal Lake to McHenry. Both arterial roads are set for widening projects.

Because of the northern long-eared bat’s endangered status, IDOT limits tree-clearing projects to Nov. 1 through March 30. That is when the bats are either hibernating or have flown south for the winter.

“The bats hibernate in caves over the winter, then roost in the trees during the summer months. The idea is that we don’t want to cut down their habitat while they are actively nesting,” Greg Gruen, the city of McHenry’s staff engineer, explained in a memo when the tree-clearing project was underway.

Kath said that whether bats would nest in those roadside trees is iffy – as is whether there are long-eared bats still in the county to protect.

“All of the collar counties have northern long-eared bat records,” Kath said, adding that those records may be very old. “Now, it is an uncommon bat in the sense you don’t catch them very often when doing bat surveys.”

The long-eared bats also prefer to roost in old-growth trees in areas with “large tracks of contiguous forested habitat,” Kath said. “When you’re talking northern long-eared bats, a typical roost tree would be old, large trees with exfoliating bark, dead or dying, with large cavities in them. You typically don’t find them in urban areas along roads.”

They also like Glacial Park near Ringwood, one of the McHenry County Conservation District parks. The district hosts an evening event there each July to teach about and then watch for bats, wildlife resource center manager Sara Denham said. This year, the event is set for 7:30 p.m. July 15. Registration is required via the district website: mccdistrict.org.

The conservation district also answers questions about bats for residents who may find one in their house or see them in their neighborhoods.

The local bats spend their summers in McHenry County but hibernate south of here in areas that stay milder over the winter, Denham said.

“In the summer, they will migrate up this way,” she said. “This is where they have their babies.”

The bat population at Glacial Park also has been hit by white nose syndrome, Denham said, noting, “We used to have quite a few more.”

The syndrome was first discovered in a cave in New York, Kath said. Researchers found piles of dead bats, or bats flying around when they should have been hibernating. They found a white fungal growth on the bats’ muzzles and holes eaten away on the wings.

“It has spread like an epidemic,” Kath said, adding that the fungus is believed to have come over from Europe, where bats have gained an immunity to the disease.

Bats also have a purpose in Illinois. While in some climates bats pollinate fruits and vegetables, here they mostly eat insects – including the corn borer moth and the soybean borer moth, Kath said.

“Bats are the sole predator of the adult moths” that lay eggs on corn and soybean plants, he said. Kath noted that bats eating those moths “save farmers an extra $3 billion to $30 billion a year” in insecticides.

“These bats are saving you $3 billion on the low end,” he said. “Hearing that is when people go, ‘Oh, I should start caring about these things.‘”