Bats are much more likely than birds to be killed or injured by wind turbines in Illinois, according to state data.
“About 22,000 bats a year are killed by wind turbines,” said Keith Shank, who tracks wind turbine collisions and endangered species for the Illinois Department of Natural Resources.
Shank said bats killed by wind turbines typically are not the same species affected by white-nose syndrome, a fungus that has killed millions of bats nationwide since first reported in New York in 2006.
In contrast, three bird deaths and one injury followed by recovery have been reported as a result of wind turbine collisions in Illinois since 2007.
Shank said about half of the state’s wind farm operators file voluntary reports on wildlife collisions with turbines. But he said that combined with operator reports and state analysis, bird deaths are thought to average about one per turbine per year.
There are approximately 2,400 turbines operating in Illinois.
Tall buildings, communications towers and even residential windows are a greater threat to the bird population, according to wildlife experts. Bird migration routes in Illinois also tend to be along relatively narrow corridors.
Bats, in contrast, migrate in large swarms, Shank said. Contrary to the popular image, he added, bat “radar” – technically known as “echolocating” – typically is used only to find food.
“They may mistake wind turbines for trees,” Shank said. “People using infrared cameras see them just fly through and make no effort to avoid the turbines.”
The number of birds killed by turbines remains a matter of national debate. As in Illinois, operators generally are not required to report the figure. Conservation groups also contend that industry reports are unreliable.
A 2013 study by the Wildlife Society Bulletin, a publication of the national wildlife conservation group, estimated that wind turbines kill 573,000 birds nationwide each year, including 83,000 hawks, eagles and other birds of prey.
The group estimated turbines kill 888,000 bats annually.
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