An unnatural death: Wind turbines may have effect on bat populations

In popular Halloween folklore, vampires are able to transform into bats.

And, of course, fiction tells us that one way to kill a vampire, and thus the bat, is with a stake through the heart.

But in areas around the United States, a new potential bat killer has emerged - wind turbines.

Since 2003, the concerns have grown so much on a national scale that in Woodford and McLean counties, government ordinances now require wind farm developers to include an avian study that shows the effects the large turbines might have on local bat populations.

In Woodford and McLean counties, an avian study conducted by Invenergy Inc. of Chicago details the type of bats in central Illinois and which ones could be affected the most, bat mortality at wind energy generation facilities, and the potential for displacing bats from the region.

“There is the Mackinaw River valley that could have some presence of bats,” Joel Link, spokesman with Invenergy, said Monday. “But we feel our turbines will be far enough from the river itself that there shouldn’t be a risk to those species.”

Biologists and other scientists who closely study bats are not so sure.

Ed Arnett, a conservation scientist with the Texas-based Bats Conservation International Inc., said several studies in recent years show that migratory bats in the Midwest could be prone to turbine death.

While no bat mortality studies near wind turbines have been completed in Illinois, in surrounding states studies have shown about four bat deaths per year can be attributed to their proximity to turbines.

Arnett said recent studies also have shown more bat deaths occurring near wind farms on the East Coast. A 2003 study showed between 25-50 bats were killed annually near turbines in West Virginia, prompting the formation of the Bat and Wind Energy Cooperative, consisting of wind energy experts and conservation specialists.

But two recent studies - one in Canada and one in Iowa - showing high incidences of bat deaths near wind farms in rural settings have particularly concerned Arnett.

Arnett admitted that bat studies are difficult to do.

For one, a study of bat mortality at a wind farm can cost as much as $80,000 because infrared cameras need to be purchased in order to observe the mammals, he said.

Despite the difficulties, the growth of wind farms and future wind energy developments is enough reason to be concerned.

“A lot of these migratory bats are encountering these facilities when they go about their migration,” Arnett said. “Cumulatively, with the currently installed (wind farms) and the projected developments which are growing, there is some cause for concern.”

Locally, people who do not support wind farms cite other reasons than bat mortality for their disapproval, such as reduction of property values and the lowering of an area’s aesthetic appeal.

The potential for bird deaths is often a more talked about wildlife issue.

But Angelo Capperella, conservation chairman of the John Wesley Powell Audubon Society, which wants Invenergy to take a more in-depth look into the impact of the wind turbines on migratory birds, said it’s harder to understand the effects wind turbines have on bats because they are more mysterious.

“On a national scale, there is a lot to be learned regarding the bat-turbine interaction,” Capperella said. “Locally, we don’t expect there to be many problems with bats, but we don’t know.”