Ingrid Kelley, a project manager with the nonprofit research group Energy Center of Wisconsin, said birds are a big issue at Altamont, but not elsewhere, simply because there are so many in the area. Raptors are especially vulnerable, she said. "If they are looking for a mouse while they are flying, that's all they are looking for. They aren't looking for a wind turbine."
She said other wind farms, in areas with smaller raptor populations, average about two fatal bird collisions annually per tower. Cell-phone towers, with their bright lights and electrical wires, "take out far more birds per tower than wind turbines."
Windmills are also killing large numbers of bats in the Appalachian Mountains. A report (.pdf), issued in September by the Government Accountability Office on wind farms' impact on wildlife, said that 2,000 bats were killed during a seven-month study at a 44-turbine site in West Virginia.
The report also highlighted the bird issues at the Altamont site, but it did not single out any other wind farms, and noted that animal mortality rates in other regions have been much lower. Not enough research has been conducted to come to any conclusions about the impact of wind power on wildlife, according to the report.
Cape Wind, a proposed offshore wind farm in Massachusetts' Nantucket Sound, has drawn strong protest from area residents. Audra Parker, assistant director of The Alliance to Protect Nantucket Sound, which opposes the project, said the location lies along bird-migration paths, and the turbines could also prove dangerous to marine mammals. "Our concern is that the project will have a negative environmental impact," she said.
Cape Wind is slowly moving through the permitting process, and could be up and running by 2008; it has already passed some key governmental hurdles, including a draft environmental impact report issued last November that favored the development. Its supporters claim the Alliance is more concerned that views of the windmills could drive down property values.
Miller said the Center for Biological Diversity successfully blocked a proposed wind farm in Southern California's Mojave Desert because it would have required building access roads in an area that is home to bighorn sheep.
He also said the FPL's plan to shut down half of the Altamont turbines is not enough. His group supports the plan in the California Energy Commission's 2004 report, which recommended that the Altamont wind farm shut down completely during the winter. A partial shutdown "is going to do something, but it doesn't go far enough," Miller said.