The green killer: Scores of protected golden eagles dying after colliding with 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.

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.

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.