Wind energy companies in Indiana are attempting to mitigate the deaths of bats during migration season by slowing or stopping their turbines at night.

Wildcat Wind Farm, which operates 125 turbines in Madison and Tipton counties, and Fowler Ridge Wind Farm, which operates 355 turbines in Benton County, have worked with the U.S. Fish and Wildlife Service on the plans, the Herald Bulletin of Anderson reported.

In return, the companies could be eligible for an Incidental Take Permit, which allows a company to unintentionally kill or injure a small number of endangered animals while still allowing the companies to operate. The plan for the Incidental Take Permits is intended to help reduce the death of bats.

Wind farm owners could be held responsible and charged with harming an endangered species without the permit.

Wildcat Wind Farm's plan requires it to slow the turbines during the night and to purchase and provide for more than 250 acres of land for summer habitat.

"Wildcat Wind Farm seeks to maximize production of non-polluting energy by the project, while conserving bats and minimizing and mitigating, to the maximum extent practicable, the impacts of any incidental take," said Larry Springer, a public relations representative for Enbridge, the Canadian company that owns the wind farm.

Fowler Ridge Wind Farm's plan requires it to shut down turbines that are turned perpendicular to the wind during low-wind times between sunset and sunrise.

Although all migratory species of bats are vulnerable, the deaths in Indiana have been most harmful to the endangered Indiana bat and northern long-eared bat, which are also facing a decline due to the deadly white-nose fungal disease that has been killing roosting areas.

Bats play an important role in the ecosystem by eating night-flying insects, including many agricultural pests.

A study from academic journal Bioscience said 600,000 to 900,000 bats are killed by wind turbines each year in the United States.

Wildlife is a frequent victim of wind farms. The National Audubon Society says wind turbines kill an estimated 140,000 to 328,000 birds each year in North America, including birds of prey such as eagles, hawks and owls.