For years the Center for Biological Diversity has been trying to get officials and operators to take action to reduce bird kills at the wind farm in the Altamont Pass. It's estimated that as many as 47-hundred birds are killed by turbines there each year.

Last week the Alameda County Board of Supervisors agreed to shut down 750 of the five thousand windmills in the Pass each winter to protect migrating birds.

Center Spokesman Jeff Miller says the county's decision is a step in the right direction.

"It doesn't quite shut down as many of the lethal turbines as we'd like, but it's considerably better than what the county was set to approve when we filed the appeal."

The board is also calling for less lethal taller turbines, to gradually replace the current ones.

The operators of the turbines have argued that tall buildings and high voltage lines are the leading contributors to bird deaths and that they're unfairly being singled out.

Windmills at the Altamont Pass provide pollution free electricity to some 120 thousand homes in northern California.