Sep 23 - United Press International

To reduce bird deaths, some 4,000 aging wind turbines in California will be idled temporarily, and some will be scrapped and replaced with newer models.

Alameda County officials approved the measure to shut down thousands of turbines for two months this winter, following a four-year study that showed the electricity-producing windmills in the Altamont Pass killed some 4,700 birds a year -- including California golden eagles -- reported the Oakland (Calif.) Tribune Friday.

Companies operating the wind farms say the new requirements -- incorporated in their new permits -- will cost them millions of dollars.

Environmental groups say the measure does go far enough and that the number of bird deaths could be reduced by 50 percent immediately if the 350 most lethal wind turbines were shut down -- and seasonal shutdowns of remaining machines from mid-November through February were enforced.