The death count of more than 60 birds a year during the last three decades worries field biologists because the turbines in the Altamont Pass Wind Resource Area -- which have been providing thousands of homes with emissions-free electricity since the 1980s -- are situated in a region of rolling grasslands and canyons containing one of the highest densities of nesting golden eagles in the United States, the Los Angeles Times reported Monday.
"It would take 167 pairs of local nesting golden eagles to produce enough young to compensate for their mortality rate related to wind energy production," biologist Doug Bell, manager of the East Bay Regional Park District's wildlife program, said. "We only have 60 pairs."
The Fish and Wildlife Service says about 440,000 birds are killed at wind farms across the country each year.
So far, no wind energy company has been prosecuted by federal wildlife authorities in the death of protected birds, the Times reported. Environmentalists have had some success -- often through litigation -- requiring the energy industry and federal authorities to modify the size, shape and placement of wind turbines, the newspaper said.
Celebrity Breakups and divorces of 2014 [PHOTOS]