Scientists Study Wind-Farm Risks to Birdsby Hal Bernton
Seattle Times, June 6, 2010
GOLDENDALE, Klickitat County -- Biologist Orah Zamora spends her days walking around wind turbines in search of dead birds and bats. Most of her surveys turn up nothing, but every once in a while she finds a carcass that may have been felled by a whirring blade.
"It's like a crime scene, and you try to figure out what happened. Sometimes, it's really obvious because you see a slice mark," Zamora says.
Zamora's monitoring at the Windy Flats project is part of a larger series of surveys to assess how the wind-power boom is impacting birds that must now share air space with the towering turbines.
The surveys, which are financed by the wind industry, indicate that wind power is a relatively minor hazard to birds. But some scientists say it is still too soon to discount the risks posed by the rush to develop Northwest wind power. They are particularly concerned with the plight of hawks, eagles and other raptors, which are large, long-lived birds at the top of the food chain.
One survey at Big Horn Wind Farm in Klickitat County estimated that more than 30 raptors were killed during an initial year of operations -- more than seven times the number forecast in a pre-construction study. The dead raptors included kestrels, red-tailed hawks, short-eared owls and a ferruginous hawk, which Washington state lists as a threatened species.
"It's just too early to say what this all means," said K. Shawn Smallwood, a California ecologist who has published numerous scientific articles on wind farms and raptor deaths. "The science is just not there yet."
There also is uncertainty about how raptors react to wind-power development, which often carves up foraging grounds with miles of new roads. Some say more studies are needed to determine if some species shy away from these areas or eventually abandon nests near the wind farms.
"Some of these projects are going up in undeveloped areas that were kind of havens for these species," said James Watson, a Washington Department of Fish and Wildlife biologist who has spent 40 years studying raptors. "These turbines are occupying some of the flight space that is their bread and butter."
Zamora works for West Inc., an ecological field-study company that has become a major contractor for the wind-power industry. The company's surveys of turbine operations, which typically last a year or more, do miss some dead birds that get quickly picked apart by ravens, vultures or coyotes. Statisticians try to account for such removals in coming up with the final survey estimates that have been released for about a dozen Northwest wind farms.
Based on that information, the wind-power turbines currently operating in Oregon and Washington kill more than 6,500 birds and more than 3,000 bats annually.
In an era of climate change and a massive oil spill off the coast of Louisiana, wind-power advocates say these deaths are an acceptable trade-off for development of a renewable energy source.
They note that house cats and other man-made hazards cause tens of millions of bird deaths each year.
Bird mortality "at wind farms, compared to other human-related causes of bird mortality, is biologically and statistically insignificant," wrote Mike Sagrillo, a consultant who writes for American Wind Energy Association.
But Altamont Pass in California, where an earlier generation of wind turbines constructed during the 1980s were densely packed into a key raptor area, offers a notorious example of wind power's toll on birds.
These Altamont wind farms have consistently killed more raptors per megawatt of power than anywhere else in the nation. Despite efforts to modify these wind farms, surveys indicate the Altamont wind farms still kill more than 1,600 hawks, eagles and other raptors annually, according to Smallwood.
The Altamont experience raised concerns among bird biologists as wind power spread to the Northwest in the late 1990s. In one of the first major projects, Florida Power & Light proposed extending Stateline wind-farm turbines into the bird-rich Wallula Gap saddle, just above McNary National Wildlife Refuge on the Columbia River.
"We told them that we need to think about this -- and so do you," recalls Mike Denny, a biologist who serves on the board of the Blue Mountain Audubon Society.
After initially brushing aside those objections, Denny said that Florida Power & Light eventually agreed to negotiations that kept the turbines out of the area and made other siting concessions to reduce the impacts on birds. "I really think they did their best," Denny said.
Considering birds' needs
In recent years, some of the biggest Northwest concerns about raptors and wind-power development have been in the plateau country of Klickitat County, whose farm fields and grazing lands offer a buffet of chukars, rabbits and other prey to birds that nest in the nearby Columbia River Gorge.
When raptors spot prey, powerful hunting instincts take over, and the birds may dive to the ground without paying much heed to rotating -- and potentially lethal -- blades. Or, they may hover in the air currents, searching for prey, and then drift into the turbines.
In Klickitat County, a new generation of bigger turbines can produce more than twice the electricity of the older models at Altamont. These projects typically have far fewer turbines spaced farther apart, helping reduce the bird toll.
Wind-power developers, after consultations with state biologists, also have agreed to relocate some turbines away from canyon edges frequented by raptors, and avoid installing them in some areas used by raptors or near their nets.
"We take the questions and concerns of wildlife impacts very seriously," said Jan Johnson, a spokeswoman for Iberdrola Renewables, which owns the Big Horn Wind Farm and which invested in conserving 455 acres of wildlife habitat on the south side of the Big Horn site, a larger conservation easement than the state required.
Still, as the industry expands in the years ahead, the raptor death toll will continue to rise. Just how much is in dispute.
One effort to estimate that industry's cumulative death toll was undertaken by West in a study paid for by the Klickitat County Planning Department.
If the industry doubled in size, that study estimated the turbines would kill 516 raptors each year in the Columbia River plateau region of Oregon and Washington. Even at those rates, the study concluded such a toll would not appear to have significant impacts on any species. But ecologist Smallwood thinks the study significantly underestimates the raptor death toll. It's difficult to determine whether these deaths would harm individual species because there aren't good estimates of the total population for most Northwest raptor species, he said.
"We can't say what [death toll] is biologically significant," he said.
Greg Johnson, a biologist who co-authored the West study, conceded that the surveys used to estimate raptor populations have large margins of error. But he said it's better to use those estimates then to "shrug our shoulders and say we don't know."
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