“They're intriguing little animals when you see them,” she said. “They're a wonderful part of our ecosystem.”

Bats eat mosquitoes, moths and other insect pests, but they are under a lot of threats beyond wind turbines.

White Nose Syndrome, a fungal disease, has hit bats hard in the United States and Canada.

Loss of habitat and declining food sources are other problems.

With spraying and other methods used to control insects in agriculture, “you've got a landscape of death from an insect standpoint” in the Midwest, said Capparella.

With so many challenges hitting together, “they're just getting hammered,” he said. Capparella said 90% of the population of Little Brown Bats has been lost.

The bats most often found at the base of Heartland's turbine were Hoary, Silver-Haired and Eastern Red bats — all bats that roost in trees, rather than roosting or hibernating in caves and old mines. “One hypothesis is they see the turbine as a tree,” said Capparella, and get hit by the blades. The tips of blades on turbines like the one at Heartland move 140 to 150 mph, he said.