As a general rule, birds of prey are not watching for giant, spinning blades. In fact, eagles, hawks and owls are not even looking where they’re going. They’re focused on earth below, scouring the grass for mice, rabbits and prairie dogs.
It’s one of the reasons raptors become the victims of wind turbines in the nation’s ever more prevalent wind energy farms, said Trina Bayard, director of bird conservation for the Audubon Society of Washington State. She compares the phenomenon to “driving while texting.”
“You’re looking down at the phone, and all of a sudden you hit something,” Bayard said.
Bird deaths at wind farms are putting wind farms under greater scrutiny, including the two owned by the Cowlitz PUD in the Columbia River Gorge near Roosevelt.
Studies of bird fatalities at the two wind farms found that the PUD’s Harvest Wind Project kills an average of 291 birds in a year, including 23 raptors. Cowlitz PUD’s much larger White Creek Wind project kills an average of 829 birds in a year, including 97 raptors. The White Creek Wind farm, with 89 turbines, went online in 2007 and the Harvest Wind Project, with 43 turbines, went online in 2009.
The death rate at White Creek was twice that of other Columbia Plateau wind farms, the studies found, while the rate at Harvest was closer to average. (Both studies acknowledge they have significant margins for error.)
None of the birds that were killed were federally protected species, said Bjorn Hedges, the plant manager at both of the PUD’s wind farms. Horned lark were by far the most commonly killed at the wind farms. Other bird fatalities included Vaux’s swift, European starlings, red-tailed hawks, great horned owls and American kestrel.
Nationwide, wind power is estimated to cause fewer than 200,000 bird fatalities each year. That’s far less than those caused by collisions with buildings (up to 976 million) or collisions with high-tension lines (up to 130 million), according to conservation groups.
Still, conservationists and regulators are turning their focus to wind power to ensure turbines don’t severely deplete bird populations already hard-hit by pesticides, oil spills and power lines. Last year, the Obama administration fined Duke Energy Renewables, Inc., a North Carolina subsidiary of Duke Energy Corp., $1 million for killing protected birds at two Wyoming wind farms. In all, the company pleaded guilty to killing 163 protected birds, including 14 golden eagles.
Across the U.S., energy companies say they are choosing their wind energy sites carefully to keep them out of the path of migrating birds. They’re also using radar and GPS signals to track birds and even shut down turbines when they get too close.
At the Cowlitz PUD wind farms, U.S. Fish and Wildlife officials have attached GPS devices to young raptors, and PUD and government officials are tracking where they fly, Hedges said.
Twenty four raptors were found dead at the Cowlitz PUD’s White Creek wind farm over a 2007-2011, according to a study conducted by a wildlife consultant. Another eight, including kestrels, hawks and an owl, were found at the Harvest Wind Project, also owned by Cowlitz PUD, over a two-year period between 2010 and 2012, according to another study by the same firm, Northwest Wildlife Consultants, Inc.
The Cowlitz PUD bird strike studies, acquired this month by The Daily News, combined actual counts of bird carcass with statistical models that account for dead birds missed by counters or removed by scavengers.
Those numbers are generally higher than other wind energy projects in the region. The studies, which were required under the terms of permits for the PUD’s wind projects, found that the average estimate for all bird fatalities at White Creek was nearly double that of other wind projects on the Columbia Plateau – 4.05 per megawatt of power generated per year compared to 2.14 bird deaths per megawatt per year average for all Columbia Plateau wind farms. The average at Harvest Wind is 2.94 bird deaths per megawatt annually.
But the bird deaths at both Cowlitz PUD projects are within acceptable levels, Hedges said.
“Neither site raised any alarms,” Hedges said, adding that he does not anticipate bird strikes at either site will become a liability for the PUD anytime soon.
Still, Bayard, of the Washington Audubon society, said the numbers from the Cowlitz PUD reports “are cause for concern.”
“The fact that these facilities seem to impact higher than average number of birds certainly warrants our attention and an open dialogue,” Bayard said.
“We are quite pleased to have options for green energy,” she said. “On the other hand, you have this very obvious mortality of birds. And trying to get a handle on what the cumulative impacts are on bird populations is something that I think nobody has really done to this point. So it remains an open question and one that we and others are quite concerned about.”
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