Federal authorities are investigating the deaths of at least six golden eagles at the Los Angeles Department of Water and Power's Pine Tree Wind Project in the Tehachapi Mountains, the U.S. Fish and Wildlife Service said Tuesday.
So far, no wind-energy company has been prosecuted by federal wildlife authorities in connection with the death of birds protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act. A prosecution in the Pine Tree case could cause some rethinking and redesigning of this booming alternative energy source. Facilities elsewhere also have been under scrutiny, according to a federal official familiar with the investigations.
"Wind farms have been killing birds for decades and law enforcement has done nothing about it, so this investigation is long overdue," said Shawn Smallwood, an expert on raptor ecology and wind farms. "It's going to ruffle wind industry feathers across the country."
Wildlife Service spokeswoman Lois Grunwald declined to comment on what she described as "an ongoing law enforcement investigation regarding Pine Tree."
Joe Ramallo, a DWP spokesman, said, "We are very concerned about golden eagle mortalities that have occurred at Pine Tree. We have been working cooperatively and collaboratively with the U.S. Fish and Wildlife Service and the California Department of Fish and Game to investigate these incidents.
"We have also actively and promptly self-reported raptor mortalities to both authorities," he said. "Moving forward, we will be ramping up further our extensive field monitoring and will work with the agencies to develop an eagle conservation plan as part of more proactive efforts to monitor avian activities in the Pine Tree area."
An internal DWP bird and bat mortality report for the year ending June 2010 indicated that compared to 45 other wind facilities nationwide, bird fatality rates were "relatively high" at Pine Tree, which has 90 towers generating 120 megawatts on 8,000 acres.
Golden eagles weigh about 14 pounds and stand up to 40 inches tall. Their flight behavior and size make it difficult for them to maneuver through forests of wind turbine blades spinning as fast as 200 mph — especially when they are distracted by the sight of prey such as squirrels and rabbits.
DWP officials acknowledged that at least six golden eagles have been struck dead by wind turbine blades at the two-year-old Kern County facility, about 100 miles north of Los Angeles, which was designed to contribute to the city's renewable energy goal of 35% by 2020.
Although the total deaths at Pine Tree pale in comparison with the 67 golden eagles that die each year in Northern California's Altamont Pass Wind Resource Area, the annual death rate per turbine is three times higher at the DWP facility. The Altamont Pass facility has 5,000 wind turbines — 55 times as many as Pine Tree.
Nationwide, about 440,000 birds are killed at wind farms each year, according to the Wildlife Service. The American Wind Energy Assn., an industry lobbying group, points out that far more birds are killed by collisions with radio towers, tall buildings, airplanes and vehicles, and encounters with household cats.
Attorney Allan Marks, who specializes in renewable energy projects, called the Pine Tree deaths "an isolated case. If their golden eagle mortality rate is above average, it means the industry as a whole is in compliance."
About 1,595 birds, mostly migratory songbirds and medium-sized species such as California quail and western meadowlark, die each year at Pine Tree, according to the bird mortality report prepared for the DWP last year by Ojai-based BioResource Consultants.
BioResource spokesman Peter Cantle suggested that those bird deaths may be unrelated to Pine Tree's wind turbines.
"It's hard to tease out those numbers," he said. "Basically, we walked around the site to find bird mortalities, which could have been attributable to a number of things including natural mortality and predators."
The death count worries environmentalists because the $425-million Pine Tree facility is in a region viewed as a burgeoning hot spot for wind energy production.
"We believe this problem must be dealt with immediately because Pine Tree is only one of several industrial energy developments proposed for that area over the next five to 10 years," said Los Angeles Audubon President Travis Longcore. "Combined, they have the potential to wipe this large, long-lived species out of the sky."