The U.S. Fish and Wildlife Service is investigating a report of an eagle killed by a wind turbine on the Minnesota-Iowa border. Pat Lund, top investigative officer for the agency's St. Paul office, declined to provide details. But he said that an investigation is underway, and the incident may have occurred at a facility that flanks the Iowa border in southwest Minnesota.

He could not say when the investigation would be complete. But if confirmed, it would be the first known death of an eagle at a Minnesota wind project.

In recent years, there have been four documented deaths and one injury to bald eagles from North American wind farms, and many more among golden eagles at one wind farm built along their migration path in California, according to the Fish and Wildlife Service.

The impact of wind farms and bats and birds is an increasingly controversial issue as wind farms proliferate across the landscape. The threat to eagles has been a major stumbling block in the wind project proposed for Goodhue County near Red Wing.The area west of the Mississippi River is a nesting and migration area for eagles.

Wind turbines at Minnesota's largest wind facility on Buffalo Ridge near Lake Benton, Minn.