Governors' Wind Energy Coalition

Wind turbines  at the Sacramento Municipal Utility District’s 102-megawatt wind farm in Rio Vista, Calif., on March 10, 2010. Wildlife experts have raised concerns about  birds being killed in collisions with wind turbines. (Ken James/Bloomberg)

It has long been the tarnish on one of the cleanest forms of energy: Wind turbines, a rapidly growing source of electricity around the world, can be deadly to birds, including rare and threatened species.

At a single wind farm near Altamont, Calif., more than 75 golden eagles die each year from collisions with the farm’s thousands of spinning blades.

Now, a study offers new hope for reducing the number of bird deaths. A paper by researchers from Colorado and Ontario says avian mortality can be sharply reduced through better decisions about where future wind farms are built.

The study examines the potential for peaceful co-existence between large raptors and rotors across Wyoming, a state with large numbers of eagles and a vast potential for wind-generated electricity. In the article, researchers Brad Fedy and Jason Tack compile data for hundreds of known eagle nesting sites and plots it against some of Wyoming’s most promising regions for wind farms. The exercise successfully identified “sweet spots,” places far removed from nesting grounds but directly in the path of prevailing winds that can keep turbines turning.

“We can’t endanger animals and their habitats in making renewable energy projects happen,” said Fedy, an assistant professor of environmental studies at the University of Waterloo. “Our work shows that it’s possible to guide development of sustainable energy projects, while having the least impact on wildlife populations.”

The researchers chose to focus on golden eagles, a species that has been famously impacted by wind farms elsewhere in the country. Roughly the same size as the bald eagle but with leg plumage and a hawk-like beak, golden eagles are common in Western states, but listed as endangered in parts of the East.

Golden eagles are among the thousands of raptors killed at the Altamont Pass Wind Farm, an older wind installation in central California. A reason for the high casualty rate, experts say, is the relatively small size of the farm’s nearly 5,000 turbines, many of them built in the 1970s.

Most modern turbines are mounted on tall towers where birds are less likely to encounter them. Still, it is important for planners of future wind farms to carefully consider nesting locations to avoid needless avian deaths that can ultimately become obstacles to a wind farm’s success, Fedy and Tack say in their article, published in the peer-reviewed open-access journal PLOS ONE.

Reducing nest site data to remove redundant and clustered data produced 1,176 total nest sites, 483 in the Northwest Great Plains (NWGP – dark gray) and 693 in the Wyoming Basin (WYB; light gray).

“Golden eagles aren’t the only species affected by these energy projects, but they grab people’s imaginations,” Fedy said. “We hope that our research better informs collaboration between the renewable energy industry and land management agencies.”