Wind turbines are responsible for the deaths of between 10,000 and 40,000 birds each year, according to the American Bird Conservancy. Debate over the significance of the threat turbine blades pose to migratory birds is about as old as the concept of wind farms themselves. It began in Altamont Pass, Calif., site of one of the first U.S. wind farms, where there were more than 4,000 turbines. Hundreds of bird carcasses were found on the farm grounds, leading bird conservationists to propagate information that wind turbines were inherently deadly to birds.

Some say counting carcasses isn't enough. That's why Illinois is changing the way it wants studies of wildlife around wind farms to be performed as more of the clean energy installations are planned around the state. Previous research has been based almost entirely on mortality counts, the process by which bird and bat carcasses are scooped up early in the morning within a several hundred foot radius of wind turbine bases. But studies now are aiming to determine a more long-range impact on avian and terrestrial creatures by examining how animals react to the sudden presence of a vertical structure soaring as high as 450 feet into the sky. The shift in practice comes as other mortality studies are under way in the area, but only a few have been completed in the state. ..."It's unfair to assume, I think, that there's no environmental effects from wind (energy)," said Keith Shank, an impact assessment specialist with the DNR. "Until we get some firm data, the problem is, people are making multimillion-dollar investments with insufficient information."

Illinois can expect bird deaths to grow as the number of wind turbines generating electricity grows. Jack Darin, president of the Sierra Club Illinois Chapter, discusses the findings of a Department of Natural Resources study that wind turbines used to generate electricity do result in the killing of birds.

Despite proof that birds and bats are being killed by the rotating blades of wind turbines, a new state report says more studies are needed to determine if anything should be done about it. ...But, the report did not call for any immediate action by the state. ''Until the impacts are better understood, regulatory action for wildlife protection is not recommended,'' the report noted.

How power-generating wind turbines affect birds and bats figured prominently in testimony Thursday as a county hearing on the proposed White Oak Wind Energy Center entered its third day. Paul Kerlinger, a bird migration and ecology expert from Cape May Point, N.J., spoke before the McLean County Zoning Board of Appeals. About 160 people attended the hearing at Heartland Community College.

A National Audubon Society chapter based in the Twin Cities has withdrawn its opposition to a proposed wind farm near the Mackinaw River on the Woodford-McLean county line. Angelo Capperella, spokesman for the John Wesley Powell Chapter of the Audubon Society, plans to be at the McLean County Zoning Board of Appeals hearing Tuesday on a special use permit the Chicago-based Ivenergy Wind LLC has requested for its White Oak Wind Energy Project. The meeting will be held at 7 p.m. in rooms 1406-1407 of the Community Commons Building at Heartland Community College. Invenergy LLC isn’t out of the woods yet, however. McLean County Department of Building and Zoning director Phil Dick said his office has received several requests from residents in the area of the proposed wind farm asking that the hearing be continued.

The Bloomington-based John Wesley Powell chapter of the National Audubon Society wants Invenergy LCC to do a little more bird watching. On Wednesday, Angelo Capparella, the chapter’s conservation chairman and a bird expert at Illinois State University, asked Woodford County zoning officials to require the wind farm company to redo a study of the potential impact its turbines might have on birds. Capparella plans to repeat the request when McLean County officials discuss the company’s plan next month.

SPRINGFIELD - Here's some legislation that's for the birds. Literally.