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Wind Power versus Raptors?

Cross-posted from Evidence-based Blog

Golden Eagle

Courtesy US FWS

An environmentalist friend of mine recently forwarded an email to me that contained the following alarming wording.

“Bald eagles are our national bird. . . The Department of the Interior and the Fish & Wildlife Service are on the verge of granting industrial wind turbine companies a “programmatic” or blanket license to kill potentially hundreds of eagles every year, for years on end.”

Like most people, eagles thrill me. Seeing, while hiking or kayaking, an eagle lifting off from a tree is still awe-inspiring. Moreover, raptors as an apex species are important to the environment because they control other populations like rats, mice, and other small mammals and insects. So this message caught my attention: Could this really be right?

Well, yes and no. Eagles, other raptors, and other migratory birds, do die in collisions with wind turbines and, at some sites, in high numbers. Probably most famous, at least in the United States, is the wind farm at Altamont Pass in California – which, because it was on the migratory flyway for many raptors, is one of the worst sites for a wind farm.

Perspective on Raptor Deaths

But, let’s step back for a minute. To start, let’s put’s put bird kills due to wind turbines in perspective. The USDA Forest Service provided these estimates of the causes of bird kills published in 2005.

Summary of Predicted Annual Avian Mortality


Mortality source Annual mortality estimate Percent composition
Buildings 550 million 58.2 percent
Power lines 130 million 13.7 percent
Cats 100 million 10.6 percent
Automobiles 80 million 8.5 percent
Pesticides 67 million 7.1 percent
Communications towers 4.5 million 0.5 percent
Wind turbines 28.5 thousand <0.01 percent
Airplanes 25 thousand <0.01 percent
Other sources (oil spills, oil seeps, fishing by-catch, etc.) not calculated not calculated


These 2005 data do show that wind turbines cause a very small proportion of avian deaths. Even so, a significant number of these are raptors.  Based on data published in 2006, the Altamont wind farms were responsible for 800-1300 raptor deaths annually, but again, for perspective, 5,000,000 raptors migrate to Central and South America from North America every autumn.

Also, based on data from a 2006 paper, nuclear and fossil-fueled power plants killed many more birds than did wind farms.  This suggests that wind is, in any case, a better alternative from the perspective of avian mortality to either fossil fuels or nuclear power as sources of energy.

The good news is that things can be and are being done to reduce the toll on raptors and other birds from wind turbines.  A critical factor may be more careful siting: Moving off ridges is one obvious thing that is being done in the case of migration routes. Another thing that has reduced bird kills is that wind turbine designs have changed: Towers built with a lattice design have been replaced with closed towers, so birds have no place to land. Old turbines spun at 60 RPM that raptors may not be able to see; newer turbines spin at 30 RPM, which may make them easier for raptors to see. Turbine height may lessen mortality of some raptors, but may increase it for others. In general, these and other changes have reduced mortality.

Why this Campaign?

So, back to the letter:  I was curious about its provenance and goggled the phrase, “license to kill potentially hundreds of eagles every year.” This led directly to the Committee for a Constructive Tomorrow  (CFACT) and its campaign to “help save the eagles” from death by wind farm.   Among other things, CFACT is a climate-change denial site, opposes CAFÉ (car millage) regulations, claims EPA rules are a threat to America’s health, etc.  According to Wikipedia, CFACT is funded by Chevron Corporation, DaimlerChrysler, the U.S. Council on Energy Awareness, the Carthage Foundation, and the Sarah Scaife Foundation. This is what we call an “astroturf environmental” organization – an organization that claims to be for the environment, but actually attacks government efforts to protect and improve the environment.

So, what is this all about? Why would CFACT create a campaign to attack the wind industry over the issue of eagles? Well, wind energy competes with traditional carbon-based forms of energy. You may or may not actually pay much attention to the specifics of the campaign, but it will be a success if it raises the question in your mind that maybe there are problems with the wind industry and maybe you should be skeptical of it. And, that’s the point—to raise doubt and lessen support for wind using emotionally charged imagery. Given the iconic power of the American Eagle image, it is no surprise that they have chosen it to deliver their anti-environmental message. For a full discussion of this strategy, I recommend Merchants of Doubt by Naomi Oreskes and Erik Conway, who studied this strategy from the tobacco industry’s opposition to cigarette regulations to opposition to climate change. We all need to become more critical in our thinking about these issues and the sources of information about them.

So, yes, we should be concerned about raptor and other bird (and bat) kills at wind tower sites. The Sierra Club, Audubon, and a number of other environmental organizations have histories of advocacy for wildlife. You can join them, support them, and volunteer for them. For information specifically about Altamont, check the Golden Gate Audubon site. But, if you are really concerned about avian mortality, you need to work on the issue of bird mortality across the spectrum of causes.

2 comments to Wind Power versus Raptors?

  • Some observations:

    1: The USDA Forest Service Bird Mortality statistics listed are eight years old, when wind farms were in their infancy. MANY more (and likely poorly sited) towers are up now. You can guarantee that the percentage of dead birds and bats due to the slicing blades has increased.
    2: To the extent that EPAs over-focus on CO2 diminishes their attention to deadly poisons and carcinogens entering our environment, CFact is on the right side of that particular narrow issue.
    3: Both Siemens and GE, largest producer of Wind Turbines, have lobby representatives fighting hard against requiring screens for their turbines, as they think their costs will go up because of them.
    4: A broad screen, with holes the size of chicken wire, mounted in a ducted fan type of annulus, marginally INCREASES the efficiency of the turbine, though its one time cost is a factor to be added.
    5: Bats do better with buildings, as their echolocation recognizes solid targets. Moving blades present a guillotine problem for them!
    6: Who funds a particular organization is less important than the integrity of the organization itself. For many years our Sierra Club apparently received some funding from Chesapeake Oil & gas, yet the environmental focus of 99.9999…% of Sierra members was unmatched and continues unabated!
    7: There’s no problem prioritizing the retrofit of Wind Turbines based upon the most bird and bat death prone areas, but belief by many in their necessity remains unabated!

  • Gary Nickerson

    Tom Wysmuller raises some good points, so I want to take them one at a time.
    1. First, wind was not in its infancy 8 years ago. But, yes, the mortality statistics are old; they were the most recent I found and yes many more towers are up than eight years ago. However, a lot has been learned and it is very unlikely that the number of kills has increased proportionately: Siting is better; new turbines kill (many) fewer birds; and on and on. If you’re interested in more recent work on this, you might want to look at Katzner et al, “Raptors and Wind Energy Development in Central Appalachia.” (
    2. CFACT’s concern with EPA is with its “hyper-regulating carbon dioxide, soot, mercury, cross-state air pollution from sources hundreds of miles away, and other air and water emissions.” Now, even if you want to delete carbon dioxide from the list (I don’t), CFACT’s is for reducing regulations on things (soot, mercury, etc.) that are health risks. And you think this is the EPA spending too much time and money on CO2? I think they want to reduce environmental regulation by EPA across the board. That’s not a “particular narrow issue” that we can support. Just look at the site and make up your own mind: Their focus is on cutting regulations everywhere and on everything. These folks are not our allies on any issue, narrow or not.
    3. Did I suggest that the wind industry was a non-profit, public interest undertaking?
    4. No comment.
    5. Yes, bats have problems with blades as well, but I notice that CFACT is not screaming about them – or about other birds. That’s because it is Eagles that are iconic and that makes them the perfect tool for their campaign. We need to think critically, keep focused and not let them divert us.
    6. I think I’ve already made it clear that CFACT does have integrity – it’s just they’re working for business, not for the environment — and I frankly don’t think they actually give a damn about eagles.
    7. I think I said we have to deal with the problem, but I want again to emphasize that even with kills at current levels, it appears obvious to me that we save more birds and raptors by replacing coal and nuclear plants with wind (not to mention solar) than with anything we can do about turbines themselves.

So, what is your reaction? Leave a comment.