Environmentally friendly efforts aren't so kind to each other in the rolling hills of the Altamont Pass.

For years, whirling rotors on some of the 5,000-plus wind turbines that line the pass have minced and otherwise killed thousands of golden eagles, red-tailed hawks and other birds of prey at a rate alarming to groups on a mission to protect them.

The unchecked bird deaths gave way in January 2006 to a legal agreement among Bay Area Audubon Societies, Alameda County and companies that operate the turbines, which are considered some of the most potent weapons in the fight against global warming.

The parties agreed to cut an estimated 1,300 annual raptor deaths by 50 percent in three years, mainly by relocating so-called high-risk turbines and shutting down some turbines during migration season, which runs from November through February. The turbines that are considered high-risk are a working turbine near a nonoperational turbine that might become home to nesting birds and turbines located in a depression among the hills where birds coasting on air currents can be drawn over a ridge and into the blades and turbines in canyons.

Now a year into the settlement agreement, there has been little progress in reducing bird deaths to levels called for in the settlement.

The Golden Gate Audubon Society, a party to the lawsuit that triggered the settlement, backs scientists' recommendation that hundreds more turbines need to be relocated and the shutdown extended in order to reach the reduction mark.

But at least one turbine operator says a year's worth of data on the number of bird deaths, which was expected to be compiled by Jan. 29, is insufficient to direct a change of course.

That company, FPL Energy, which operates roughly half of the turbines, urges further analysis of the data before making changes.

One thing is clear to both sides: Bird deaths will continue as long as there are turbines in the pass.

"There's just no silver bullet for Altamont Pass," said Elizabeth Murdock, director of the Golden Gate Audubon Society.

It's a stalemate that has both parties calling for a balance that would allow companies to maximize use of the roughly 40 mph winds that blow through the pass while not harming the raptors, including the federally protected golden eagle, whose nesting population in the pass is among the world's largest.

The best way to reach that balance is as elusive now as it was a year ago, observers say.

Steve Stengel, a spokesman for Florida-based FPL Energy, said the company wants to identify a long-term solution to the bird-death issue before relocating any more turbines, something he said would be premature without further analysis.

"We agree that something needs to be done to reduce the number of bird fatalities in the Altamont, but we need to take a balanced approach," Stengel said.

A team of scientists appointed by Alameda County officials to review the bird-death issue believes more needs to be done.

The panel recommended in December that 304 more turbines be relocated and said an additional 102 turbines might need to be relocated if the shutdown did not carry over into January and February. Even then, the scientists opined that a four-month shutdown might only reduce deaths by roughly 30 percent.

The scientists a year ago recommended relocation of about 150 turbines deemed at the highest risk for killing birds.

Rep. Jerry McNerney, a wind energy consultant before he was elected in 2006 to represent the district that includes the Altamont Pass, urged patience. He called the current plan "reasonable" and said the deaths will begin to slow as companies change out older, shorter, less efficient turbines with taller, more efficient ones. One theory states that the taller turbines may kill fewer birds.

"I don't think we should make drastic conclusions in one year," McNerney said.

Contact reporter Jake Armstrong at (209) 239-3368 or jarmstrong@recordnet.com.