Wind turbines killing more golden eagles in Wyoming than expected

Golden eagle, photo by Martin Mecnarowski

‘These numbers can add up alarmingly fast’

By Sophie Osborn

As industrial-scale wind energy development has expanded in Wyoming, observers have grown increasingly concerned about potential impacts to our wildlife. Over the last few years, many Wyomingites have worked diligently to protect the iconic greater sage-grouse from this latest threat to our sagebrush landscapes.

But recently, the plight of the golden eagle has quietly captured the attention of federal and state agencies and, increasingly, concerned citizens.

Evidence is mounting that Wyoming wind farms are killing more golden eagles than expected. Measures to try to reduce eagle impacts could have a major effect on the number and location of wind turbines that are ultimately deployed in the state.

High numbers of golden eagles killed at the Altamont Pass Wind Resource Area in California in the early 1990s alerted the world to the threat that wind turbines pose for these majestic birds.

Better turbine designs and improved siting of wind farms offered hope that such fatalities could be addressed and mitigated.

But eagle fatalities at newly constructed wind farms in Wyoming suggest that such measures, while important, are not a panacea.

Wyoming has long been a stronghold for breeding golden eagles and is also an important wintering area for many eagles that originate from parts north. These long-lived birds usually don’t begin reproducing until they are about five years old and typically produce only one or two young per year.

As a result, deaths of adult eagles, which typically have low mortality rates, can have significantly adverse effects on populations.

Over the last few decades, golden eagle populations have declined across the West.

In response to these declines and the serious threat posed to these birds by wind turbines, the U.S. Fish and Wildlife Service recently developed an eagle conservation plan that provides guidance for how to reduce eagle fatalities at wind farms.

Wyoming’s wind-power build-out could pose a serious risk to eagles

According to the U.S Fish and Wildlife’s Patricia Sweanor, in a presentation given at the Raptor Research Foundation September 2010 conference (click here for the abstract), fatality rates in one geographic area in Wyoming have approached one eagle per 39 wind turbines per year.

In a nearby area, with an abundant prey base, fatality rates have been as high as one eagle per 13 turbines per year (the equivalent of approximately five eagles killed per year at one 66-turbine wind farm).

These numbers can add up alarmingly fast.

Wyoming currently has approximately 1,000 turbines operating and another thousand are planned for construction in the next few years.

The U.S. Fish and Wildlife Service estimates that the eventual build-out of wind farms in Wyoming could consist of 10,000 turbines—posing a serious risk to eagles if more stringent siting measures and best management practices are not adopted.

Golden eagles and bald eagles are protected by the Bald and Golden Eagle Protection Act and by the Migratory Bird Treaty Act. Both federal laws were developed to help protect our nation’s bird populations. The Fish and Wildlife Service is charged with implementing these federal statutes.

Killing eagles—even through unintentional activities such as harnessing the wind for energy—violates federal law, though currently no wind farm has ever been prosecuted for its actions or had to pay fines (unlike utility companies, oil and gas companies, and other energy developers that have inadvertently killed birds through their activities).

The Fish and Wildlife Service can grant permits that allow for the killing or “take” of eagles, but according to its new eagle conservation plan, companies will have to adhere to strict siting measures and conservation practices before they can procure such permits.

In addition, the agency will require that wind companies offset those eagles that they do kill by contributing to a conservation fund or by retrofitting dangerous power poles to save an equivalent number of eagles from collisions and electrocutions in the same region.

Photo by Dan Hayward

The Fish and Wildlife Service is striving to achieve a no-net-loss of eagles so it can meet its goal of sustaining stable or increasing eagle populations.

The Wyoming Outdoor Council recently submitted extensive comments on the Service’s draft Eagle Conservation Plan Guidance; click here to see these comments.

We support the agency’s plan to better protect eagles from industrial-scale wind energy development.

Last year, we included many of the advanced conservation practices that the federal government is currently proposing in our “Wind energy: doing it right in Wyoming” brochure.

However, in our recent comments to the U.S. Fish and Wildlife Service, we also suggested some additional protective measures such as conducting more frequent surveys to better document eagle use of a proposed project area prior to siting turbines, and the temporary or permanent shut-down of turbines that kill a disproportionate number of eagles.

The Council supports renewable energies such as wind energy because they could—if coupled with increased energy efficiency—help reduce toxic emissions and the use of fossil fuels.

However, we also recognize that some areas are inappropriate for industrial-scale wind development.

Where wind energy development poses little threat to wildlife and does not disrupt cultural resources and cherished viewsheds, we urge wind companies to remain in compliance with federal statutes by adopting conservation practices that will reduce adverse effects to wildlife.

Wind developers must do their utmost to live up to the “green” reputation that they often tout.

Truly green energy will exploit the Wyoming wind, but will do so while sustaining Wyoming’s wildlife and iconic vistas.

Contact: Sophie Osborn, Wyoming Outdoor Council, 307-742-6138;

Sophie Osborn is a wildlife biologist and the Wyoming Outdoor Council’s wildlife program director. She is the author of the award-winning book Condors in Canyon Country.

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5 comments on “Wind turbines killing more golden eagles in Wyoming than expected
  1. charlie henderscheid says:

    i feel that you never explained the matter of how the golden eagles are being killed from the wind turbins.

  2. admin says:


    Thanks for your comment.

    Golden eagles are killed by wind turbines when they collide with the wind turbine blades. Golden eagles appear to be particularly vulnerable to strikes by turbine blades. Although the massive blades appear to be moving slowly, the speed at their tips can exceed 180 mph on the standard 1.5 megawatt (MW) turbines and the sweep of the blades covers more than one acre. It’s believed that eagles may not always see the blades moving toward them when they are focused on or pursuing prey.

    —Sophie Osborn

  3. GeorgeG says:

    Remember why bald eagles and golden eagles became protected species? Think about it? Remember mercury pollution? Remember acid rain? Welcome to Wyoming, one giant smokestack that produces 96% of its power the dirty way.
    Seems the folks in Wyoming, although famous for their flying eagle hunts, are quite willing to kill many creatures, people too. Everytime you flip a light switch your killing eagles and us … nice going. Lead poisoning due to feeding on dead carcasses is a serious problem for eagles but in Wyoming you can add flying lead from dumb jackasses. In Wyoming, 44% of golden eagles tested had toxic levels of lead. And what’s a little poison bait between friends. Another fine Wyoming tradition. Not a problem.
    “Removal of any active migratory bird nest or any structure that contains an active nest (e.g., tree) where such removal results in take is prohibited” except of course in Wyoming if you’re digging a mine. So let me summarize, shootong, poisoning, destruction of habitat is just fine – it’s only wind turbines that might be a minor threat to the Wyoming coal industry that’s a problem,

    • admin says:

      We share your deep concerns about the serious threat that mercury pollution, DDT (which was a principle cause of the Bald Eagle’s decline), acid rain, lead bullet fragments in carcasses, energy development, shooting, poisoning, habitat destruction, and other threats pose to birds and other wildlife. We work actively on many of these issues and believe that mitigating their impact on our wildlife is essential. In raising concerns about the threat that wind turbines pose to Golden Eagles, we in no way intended to diminish the many other threats these birds face. But we think it’s important for everyone to be aware that there is no such thing as a free lunch when it comes to energy development. All such development – including wind energy – has associated costs. We hope to raise awareness of these costs so that we can all do our best to mitigate them and to find a balance between producing the energy we need to live and helping the wildlife that we love to thrive. Clearly energy conservation is our best solution and we encourage everyone to do their utmost to reduce their energy consumption – in Wyoming and beyond.

      –Sophie Osborn

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