California's attempts to switch to green energy have inadvertently put the survival of the state's golden eagles at risk.
Scores of the protected birds have been dying each year after colliding with the blades of about 5,000 wind turbines.
Now the drive for renewable power sources, such as wind and the sun, being promoted by President Obama and state Governor Jerry Brown has raised fears that the number of newborn golden eagles may not be able to keep pace with the number of turbine fatalities.
Not eagle friendly: Scores of Golden Eagles have been dying each year after colliding with the blades of about 5,000 wind turbines
The death count along the ridgelines of the Bay Area's Altamount Pass Wind Resource Area has averaged 67 a year for three decades.
The 200ft high turbines, which have been operating since the 1980s, lie in the heart of the grassy canyons that are home to one of the highest densities of nesting golden eagles in the US.
'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,' field biologist Doug Bell, manager of East Bay Regional Park District's wildlife programme, told the Los Angeles Times
. 'We only have 60 pairs,' he added.
© The Los Angeles Times
Grand scale: The death count along the ridgelines of the Bay Area's Altamount Pass Wind Resource Area has averaged 67 a year for three decades
© The Los Angeles Times
Field biologists, monitoring the birds, say it would take 167 pairs of local nesting eagles to produce enough young to compensate for the loses. Currently they only have 60 pairs
Nationwide, about 440,000 birds are said to be accidentally killed at wind farms each year, as well as thousands more bats. With the government pushing for more wind energy farms, that statistic is likely to rise.
Another recovering species, the California Condor, is also said to be at risk from the giant blades.
'We taxpayers have spent millions of dollars saving the California condor from extinction,' Gary George, spokesman for Audubon California, told the Times
Wind power, which is being promoted by President Obama, right, and California state Governor, Jerry Brown, left, has raised fears about golden eagles
'How's the public going to feel about wind energy if a condor hits the turbines?'
Newer carbines are said to be less harmful to birds and the U.S. Fish and Wildlife Service has asked power bosses to turn off the wind machines during times of heavy bird migration.
But the moves have done little to protect the golden eagles, which weigh about 14 pounds and stand up to 409 inches tall.
Their flight behaviour makes it difficult for them to navigate through masses of wind turbine towers, especially when they are easily distracted by prey on the ground.
'The eagles usually die of blunt-force trauma injuries,' said Mr Bell.
'Once, I discovered a wounded golden eagle hobbling through tall grass, about a quarter mile from the turbine blades that had clipped its flight feathers.'
'A wind farm owner once told me that if there were no witnesses, it would be impossible to prove a bird had been killed by a wind turbine blade.
My response was this: If you see a golden eagle sliced in half in a wind farm, what other explanation is there?' he added.