LIVERMORE (AP) — While everyone agrees huge numbers of birds are dying in the wind turbines of Northern California’s Altamont Pass, they don’t agree on how and why they are dying.
According to counts conducted by Alameda County from 2005 to 2012, up to 4,600 birds die on Altamont wind farms every year. But the counts indicate that 44 percent of the deaths over the past three years of the study occurred while turbines were not operating, leading some to hypothesize that other factors, including natural causes, predators and even rat poison, might be to blame, the Contra Costa Times reported Saturday.
Another study funded by wind companies will look at what other factors besides turbines could be killing birds. That study will be conducted by consulting firm IC International and is scheduled to be presented in July.
ICF International project manager, Doug Leslie, said the Alameda County’s study makes a strong case that predators are to blame.
“We shut things off in the winter and we expect birds to stop getting killed, but that hasn’t happened,” Leslie said.
The study to be presented in July “will provide evidence of what we already knew, that there are birds of prey out there that kill other birds, and those could be confused with the (turbine-related) bird deaths,” Leslie added.
Environmentalists, however, point out that birds still die by running into the stationary structures during heavy fog or because they’re scanning the ground for food. They are also often electrocuted or maimed by striking power lines linked to the wind farm’s infrastructure.
Liz Leyvas, a biologist who has counted dead birds in the Altamont for both ICF and as an independent researcher, said a majority of deaths are caused by direct contact with turbines, whether they are on or not.
“Usually if you see dead birds in a wind farm, it died in a turbine,” Leyvas said. “You know because a wing or a limb is missing. The larger birds, like sea gulls, owls, vultures, hawks and eagles, those are dying because they are getting hit.”
Three of the four major wind companies with turbines in Altamont Pass agreed that by October they would replace older-generation turbines with fewer, more efficient, more bird-friendly turbines.
Still, no one is certain how well repowering will work and how many bird lives will be saved — which means the debate over the role of the turbines is likely to continue.