SkepticblogSkepticblog logo banner

top navigation:

Wind Turbines and Birds: The Cuisinarts of the Skies?

by Brian Dunning, Jan 07 2010

The main argument against wind turbines by environmentalists is that the spinning blades kill birds. When I heard this, I was skeptical.

Digging through the Intertubes, I found that it’s true. Each large, commercial wind turbine in the United States kills an average of about two birds per year. This varies a lot based on where the wind farm is. Some are right in bird migration paths, and some aren’t. But the average is about two per year per turbine. In 2001 there were 3,500 operational wind turbines in the U.S., for a grand total of 6,400 birds killed.

Sounds like a lot, I suppose. But I wanted to know how many birds died from other manmade causes. Here are those numbers (based on the most common annual estimates I found):

Window collisions 1,000,000,000
Powerline collisions 174,000,000
Hunting 100,000,000
House cats 100,000,000
Pesticides 67,000,000
Automobile collisions 60,000,000
Communication towers 40,000,000
Oil extraction 1,000,000
Wind turbines 6,400

The granddaddy of human-caused bird population decline is habitat destruction. Numbers are not available, but it’s said to dwarf the causes listed above.

But even that pales in comparison to natural bird deaths. About one third of all birds die in collisions with natural objects, like rocks, trees, or the ground. Most of these are young birds learning to fly.

However, simply that more birds are killed by other causes doesn’t justify the incremental increase imposed by wind turbines. The entire argument is a non-sequitur, technically speaking. But it’s not completely irrelevant, in that it does put the issue into proper perspective.

It doesn’t even address the ongoing death toll to birds from particulate air pollution caused by coal and oil burning power plants, which is what we’re left with when alternative energy sources are taken off the table for “environmental” reasons. I couldn’t find a number for this, but I’ll wager it’s at least as much as it is for humans. As many 100,000 people die each year, in the United States alone, from particulate air pollution from coal and oil burning power plants. I don’t know how many are killed by the environmental effects of wind turbines, but I think it’s safe to say the number is lower.


Sagrillo, Mick. “Putting Wind Power’s Effect on Birds into Perspective.” Wind Energy Technical Info, 2003. Web. Jan 6, 2010. <>

Curry & Kelinger. “What Kills Birds?” Curry & Kerlinger, LLC. Web. Jan 6, 2010. <>

Erickson, W., et. al. “Avian Collisions with Wind Turbines: A Summary of Existing Studies and Comparisons to Other Sources of Avian Collision Mortality in the United States.” National Wind Coordinating Committee. Aug 2001. Web. Jan 6, 2010. <>

ACS News Center. “Air Pollution Linked to Deaths From Lung Cancer.” American Cancer Society. American Cancer Society, Inc., 6 Mar. 2002. Web. 21 Dec. 2009. <>

59 Responses to “Wind Turbines and Birds: The Cuisinarts of the Skies?”

  1. Dax says:

    Although your assessment seems to be correct, this does not account for migration patterns nor does it account for the barotrauma inflicted on bats (Baerwald, et al. 2008). Of course, there’s also the issue of numbers: there are more house cats and windows in the world, compared to a relatively few wind turbines.
    Baerwald, E.F., D’Amours, G.H., Klug, B.J., Barclay, R.M.R.
    Barotrauma is a significant cause of bat fatalities at wind turbines
    (2008) Current Biology, 18 (16), pp. R695-R696.

    • I’m not sure what you mean by “doesn’t account for migration patterns”. The averages and totals include wind farms that are in migration patterns and those that are not.

      • Dax says:

        Yes, the average (which by itself has statistical implications)… but the problem with migration patterns is that these will shift due to human intervention (flight paths near airports, buildings, wind turbines, even high speed rail-systems) and these shifts by themselves impact the populations a lot, too. It might reduce direct deaths caused by the wind turbines, but the change of migration paths could lead to increased indirect deaths.

  2. Trimegistus says:

    Environmentalists loved wind power until people actually started building turbines. They love solar now — but wait until large photovoltaic farms start being built in deserts. Environmentalists only like forms of power production that don’t exist. Because the point isn’t finding a clean way to produce electricity, it’s just a rhetorical ploy to conceal their fanatical hatred of technological civilization.

    • Max says:

      Who are these environmentalists?
      Here’s what Greenpeace says.

      Myth: Wind turbines threaten bird populations.

      Fact: Studies show that for every 10,000 bird fatalities, less than one is caused by wind turbines. For comparison, cats cause about 10 percent of bird deaths and nearly half are caused by collisions with buildings or windows.

      In fact, a recent study published Intergovernmental Panel on Climate Change shows that 40 percent of all species could face extinction because of global warming.

      Monitoring of existing wind farms suggests that with proper location and construction, there is no adverse impact on bird populations.

      It’s important for wind farms to conduct a thorough analysis of the risk to bird life as part of the environmental impact assessment of every proposal. With rigorous review, thorough monitoring, and sensitive design, wind power can be deployed without significant harm to birds (and other wildlife).

      • Beelzebud says:

        Gee I thought environmentalists were all fanatics that hated technological civilization.. What gives? They sound reasonable there, you must have made that up!

    • Max says:

      Here’s Audubon’s Position on Wind Power

      Summary: Audubon strongly supports properly-sited wind power as a clean alternative energy source that reduces the threat of global warming. Wind power facilities should be planned, sited and operated to minimize negative impacts on bird and wildlife populations.

    • Beelzebud says:

      Going for the Golden Strawman Award? I want to thank Max for doing some actual research, and not just spouting off a bunch of nonsense.

      If you’re going to make blanket statements against environmentalists, you could at least check out the positions of the people you’re trying to criticize.

    • tmac57 says:

      “it’s just a rhetorical ploy to conceal their fanatical hatred of technological civilization.”
      Sounds like and extraordinary claim to me. Your move Trimegistus.

  3. Dax says:

    Trimegistus, I agree. I think that the types of environmentalists you’re talking about are actually a major cause of the increasing army of “climate skeptics”, too. With their everlasting talk of doomsday and unsubstantiated claims of ‘green salvation’, the environmentalists formed a new eco-ideology far removed from reality.

    Along those lines, a rather well-renowned ecologist at the university I attend once had the audacity to say that our efforts to conserve the yellow river dolphin is a waste (in which he had the science to back him up), generating a shit-storm from the environmentalist camp. How could he say such a cruel thing! We need more money to save that species of dolphin, of which not enough individuals are alive to create a genetically diverse and viable population! *cry*

    One the other hand we have the “climate skeptics”, who are eagerly building up their own non-eco-ideology, and the science is removed from the discussion.

    • Max says:

      Here’s a Wall Street Journal opinion piece by a climate skeptic, titled “Windmills Are Killing Our Birds.”
      He’s upset that ExxonMobil was fined for killing protected birds but wind-power companies escape prosecution.

      Why aren’t wind companies prosecuted for killing eagles and other birds? “The fix here is not easy or cheap,” Mr. Lee told me. He added that he doesn’t expect to see any prosecutions of the politically correct wind industry.

  4. Wind turbine bird deaths are clearly minimal. All that can be said is that as we build further wind infrastructure, we should give some priority to placement to avoid bird and bat populations.

    There are other threats to bird populations. Building with glass seem to be #1 – and not easily fixable. There are products that minimize bird collisions with glass on buildings, but phasing them in will take decades (and it does not even seem to be a priority at the moment).

    One point of clarification – even if death from “natural” causes is dominant, that is not really the point. The question is – how many excess deaths are there from specific causes and what is the impact on the overall population of specific bird species. We also need to consider cumulative impact – total excess deaths.

    One factor not even listed is invasive species. The European starling has causes havoc on local bird species.

    No doubt, birds will evolve and adapt to all these factors – the question is what will be the impact of species diversity in the meantime. For purely selfish reasons, I like bird species diversity.

    • Dax says:

      On a sidenote, Dr. Novella, you might enjoy some of the research by Dr. Bearhop at the University of Exeter. At one of the most interesting seminars I attended last year, Dr. Bearhop showed how he uses stable isotope analysis to determine where bird populations come from, what they eat during migration, and how this all ties in with migratory, sexual, and overall bird fitness. Interesting stuff.

      See, for instance:
      Inger, R., Ruxton, G.D., Newton, J., Colhoun, K., Robinson, J.A., Jackson, A.L., Bearhop, S. (2006) Temporal and intrapopulation variation in prey choice of wintering geese determined by stable isotope analysis J Anim Ecol 75(5), 1190-1200.

    • Robert E says:

      I think I agree with you Steven…if I am understanding you correctly. The number of birds that die of natural causes (even if you limit this category to 1/3 of those dieing when learning to fly) is completely and utterly irrelevant to the discussion. 100 percent of birds die, and near 100 percent die from “natural” causes, if you exclude hunting, buildings, etc, from the equation. As a hard core environmentalist, I have heard my peeps talk at lengthen about the fact that wind mills kill birds. But I have never heard, a statement following that attempting to justify that wind turbines should therefore be banned. All environmentalist love wind mills. Well unless you are a fake environmentalist like the Kennedy’s, and fight to prevent wind mills from being put out in the ocean, because it would ruin their view…jerks (but I digress). To me, and all the environmentalists I have read and heard talk about the issue of wind mills killing birds have all brought it up not to disparage wind mills, but instead to urge that we take care in where we place them, and that we think of solutions to minimize the impact.

      We are part of the ecosystem. As parts of the ecosystem, we cannot help to effect it. All the environmental “ethic” is you will, argues is that we should be working to minimize as much as possible our effect on the planet.

  5. Interesting. If the rate of bird kills/windmill remains constant while increasing the number of windfarms (which is an assumption that may or may not turn out to be correct), increasing the number of windmills even 100 fold will not move it up in that list as a major cause of bird deaths. Even a 1000 fold increase only bumps oil extraction.

    However, Dr. Novella is right, you do have to consider the total excess deaths, when the number gets to be problematically high, and what you you can do to keep the number acceptably below that point.

    Of course conservation can be a tricky thing. You also have to keep in mind the net influence man has had on bird populations. We have done all sorts of things that result in excess bird deaths as discussed in the post and comments, but we have also eliminated many predators and their habitats as well. The net increase in bird deaths (assuming the likelihood that the net is an increase) could be significantly lower than the gross. It seems unlikely that I would be the first one to think of this, so somebody probably has some good estimates on this already.

    • MadScientist says:

      For wind power to become a significant source of electricity, we are indeed thinking of perhaps a 10,000-fold increase over what is already deployed. The figures are staggering; even if governments committed to such an enormous deployment, we’re looking at several decades to get the job done – assuming what is planted out there doesn’t need replacement during that period. Human power consumption is enormous; replacing the current technologies with something else is quite a challenge.

      • tmac57 says:

        So what point are you trying to make here. Is it ‘why bother’? Or ‘it can’t be done’? Every major change in society has always had challenges to be met. It is up to us to decide if we are going to act or to use Cheney’s phrase, to keep ‘dithering around’. Look at how the U.S. was able to ramp up military ship building during WWII. If you had asked anyone prior to that if it was possible to reach that level of out put in such a short time, they probably would have laughed at you.

  6. I guess you also have to keep in mind that the numbers provided don’t show any breakdowns.

    If you kill 6400 birds a year at one turbine, and none in the rest, that’s a little different than killing two birds at each and every turbine, especially if that lethal turbine is located in an area more ideal for wind turbine expansion than the others.

  7. Beelzebud says:

    So which environmentalists are opposed to wind power? You didn’t cite one group as being against it.

  8. Lone Wolf says:

    Never let the numbers get in the way of a good story. Idiots will still use the “Wind turbines kill birds!” The actualy number do not matter.

  9. Laura says:

    I bet you’re a shill for BigWind!Thought this topic wouldn’t draw much controversy? jk ;)
    I really expected aircraft to make the list. Last year, the heroic emergency landing of that DC 10 in the Hudson River drew the public’s attention. A double bird strike (the 2 birds with one stone metaphor comes to mind)disabled both jet engines.Apparently, bird strikes aren’t uncommon.
    When John Denver crashed and died, I remember some expert surmising that he could have hit a bird. Since he was in a lightweight-type craft, it was plausible explanation. That was the only other time I had heard about this.
    I wonder why cats are considered separately from natural causes. Because they’re domestic animals, it’s our fault for keeping them as pets? What about ferral cats? Seems that death due to animal predators would be a more appropriate category. But heck! I’m no expert, so I’ll place my all of my trust in the people with advanced degrees in ornithology .

  10. SeanG says:

    Is there a breakdown of the specific bird species killed? 6,400 seaguls, starlings, or Canada geese would be doing us a favor in Wisconsin. But 6,400 Whooping Cranes would wipe out that species here almost 100 times over.

    This is an issue that gets discussed here a lot since the Horicon marsh is a major migratory route.

  11. rob says:

    just a small note, everyone here seems to be concerned with environmentalists or how many birds die from other factors and having a good argument about it.
    while i’m thinking a simple colour change from white to say red or instalation of whistles on the ends of the blades may mute the whole argument.
    just a thought

    • MadScientist says:

      I don’t believe whistles etc would work (but it won’t hurt to try somewhere) since most types of birds seem to grow accustomed to fairly regular sounds and are no longer spooked nor consider the sounds as any sort of warning. When you are near these things you can hear the “whoop” noise of the blades as they spin; personally I don’t think it’s loud enough to bother anyone unless they live at the foot of the turbine, but they are certainly loud enough to be heard at some distance (well, heard by humans anyway). I suspect even if the birds were aware of the blades, they’d still fly by and get their timing wrong now and then – which is probably what is already happening. After all, how many birds do you see flattened on the roads – you can hardly claim they’re not entirely unaware of the traffic.

    • Max says:

      Build communication towers to look like a giant scarecrow :-p

    • tmac57 says:

      So far sonic devices have been shown to have little effect, but work continues to try to mitigate the harm. Careful site selection is apparently one of the most effective measures used at this time. Regarding the environmentalists being anti-technology, there are nuts on every side of any issue, but I think that it is clear that environmentalists as a group, would like to see clean energy technologies displace fossil fuels. Most rational people aren’t Luddites. I think this can be a win-win situation for everyone if done properly.

      • Trimegistus says:

        If they’re so committed to clean energy why are they so fanatically opposed to nuclear power?

      • CW says:

        Primordial fear of a nuclear meltdown and concern over where to store the radioactive waste. Which I believe both are very exaggerated. I heard that uranium supplies are running low, and its very expensive to obtain – any truth to this?

      • Max says:

        Also, fear that nuclear power leads to nuclear weapons.

      • tmac57 says:

        There are nearly intractable political problems with disposal sites, even if the dangers are exaggerated. Also, the lead time for engineering, and permitting are daunting. The economics and other factors don’t seem to favor nuclear since the upfront costs are so high. Many former critics of nuclear power have changed their mind, as they see it as still a better alternative to coal, but unless there is someway to streamline the engineering and permitting process, and solve the political problems of waste disposal, then nuclear will probably not have much of a future in it’s present form. There may be some technological breakthroughs that may turn the tables in favor for nuclear in the future though.

      • Larry Taylor says:

        Until the current ongoing storage problem from contamination of waste is addressed, nuclear power is not viable. Just look at Hanford, where we are – in essence – just waiting to pollute the groundwater – again, in essence – forever. I like nuclear as a concept, but it is far too expensive – especially when it needs to have it’s insurance subsidized by the government, as opposed to being paid for by rate payers.

    • rob says:

      this article is fairly old at this stage and i’m sure no one will notice but my change of colour idea may yet work, not for the reason i was thinking however and also purple not red.

  12. Ian Monroe says:

    Mostly I think this is an argument of NIMBYist, not environmentalists at all. Overall wind turbines have broad support for their environmental advantages, as seen by the ever-cautious Obama often referring to them.

  13. prophit1970 says:


    When barotrauma is sufficient to fell a bat from the air, it has been strong enough to tear a critical amount of lung tissue. If barotrauma conditions are not fully sufficient to kill, some tissue damage would occur, including other tissues besides lung. The surviving wounded bats would serve as an opportunity for pathogens to exploit the breaches in the barrier component of the mammalian immune system.

    Can anyone help me find a flaw in my thoughts above?
    I’ve had a subscription to the Skeptical Inquirer since 1984, and I appreciate the value of a vigorous and thorough debunking effort (whether or not it discovers bunk).

    If no flaw can be found, only then am I inclined to suspect that the threshold for White Nose Syndrome fungus was crossed by the time that, according to Wikipedia:
    – “Maple Ridge Wind Farm became fully operational in January 2006. The wind farm is located on Tug Hill in Lewis County, New York”
    – “White nose syndrome (…) was first identified in several caves near Albany, New York in February 2006.”

    “The 195 Wind Towers in operation, make Maple Ridge Wind Farm the largest wind tower project east of the Mississippi River.” – Lewis County Chamber of Commerce


    • LKL says:

      It’s an interesting hypothesis, but would need huge amounts of research to back it up. Yes, the appearance of whitenose has somewhat coincided with the appearance of wind towers; however, it also coincided with billions of other novel events.

      For example, excavation and the breaking up of earth in general tends to release fungal spores, as in human valley fever; what farming or excavations or have been done near the roosts or along the migration routes of the bats?

      • prophit1970 says:


        It would not require too great a commitment to begin the investigation. Full-body bat necropsies should be conducted, searching for precisely this form of damage. Comprehensive histologic findings could be analyzed by barotrauma physicians and researchers.

        Lung isn’t the only mammalian tissue to rip from the Bends. That there should be other damage to bats seems clear, so I would expect that an investigation could firmly and swiftly determine if this is happening.

        Investigations of the early history of the fungal epidemic would be a separate matter. I think that’s the portion of the inquiry to which you alluded, where a much greater amount of research would need to be committed.

  14. catgirl says:

    I am curious about how these numbers are even calculated. Is it based on human observation of birds hitting wind turbines or by counting dead birds on the ground near them? Or is there some other way that they figure this out?

  15. Gordo says:

    As someone else noted, species breakdown is very important. As far as I know, the majority of the birds killed by wind turbines are predatory (e.g. Raptors), which make up a small percentage of the overall bird population.

    So your argument ends up being a straw man. That doesn’t mean that the overall argument is not correct, just that the statistics are not particularly meaningful in a conservation context. A similar argument might be made for Bear traps. Look there are only 2000 bears killed by bear traps, but millions of wild animals are killed by cars….

    Again, before people accuse me of being anything in particular, I’m not at all sure that wind turbines do all that much harm.

  16. sonic says:

    Reading this was very eye opening and caused me a great deal of relief. Thank-you for the fine article.

  17. I’ve driven by a wind farm and oddly enough found one with a KFC in a neighbouring town. An innocent franchise placement or a cover up. You decide.

  18. Mark Schaffer says:

    Hi all,
    I just want to note that if wind were to replace many conventional fossil fuel plants the overall number of bird deaths would actually drop.

  19. I’m afraid I think the article is misleading. While I think wind turbines are good for the environment and a net boon for the birds compared to the alternatives, the values cited in the article seem out of sync with the sources he listed. Here’s a cut and paste of a paragraph:

    Table 4 contains the average fatality estimates for each wind resource area, the overall estimate of bird collisions per turbine per year for all sites, and total fatality projections based on the
    approximate estimate of 15,000 operational wind turbines in the U.S. by the end of 2001. The average number of avian collision fatalities per turbine is 2.19 per year. Therefore, on average, we estimate approximately 33,000 birds (range 10,000 to 40,000) die annually from collision with wind turbines in the United States (assuming 15,000 turbines). Species composition data indicate that approximately 14.0% of the projected fatalities are non-protected birds (house sparrows, European starlings and rock doves), and excluding these non-protected species yields an estimate of approximately 28,500 (protected) birds. We estimate approximately 6,400 birds will die annually outside California at the 3,500 turbines estimated to be in operation by the end of year 2001 (Table 4). Species composition data outside California indicate 3.3% of the
    projected fatalities are non-protected birds; excluding these non-protected species yields an estimate of approximately 6,200 avian fatalities per year.

    Rates for raptors in California seem different than elsewhere and the range of bird risk varies widely. I urge everyone to look at the resources provided before reaching a conclusion.

    Given the differences in fatality rates, and some indication that turbine design and placement are factors, it seems (to me) logical that steps can be taken to reduce impact on wildlife and still providing power.

    • Max says:

      If we compare the rates, it’s still about 2 deaths per year per wind turbine, versus 500 deaths per year per communication tower. There are an estimated 80,000 towers, and I don’t know how many wind turbines are being planned.
      Another statistic to consider when comparing wind turbines to oil extraction is the number of deaths per unit of energy produced.

      • I found it interesting that the raptor deaths were almost entirely in California. That really argues location (though it should also be noted that California had about 9:1 as many wind turbines as the rest of the country. That say something.

        I found it telling that early wind turbine designs, according to the text, seemed to be more deadly, with the implications that advances in design might also reduce bird loss.

        Sounds like interesting paths to pursue.

  20. Jeshua says:

    Surprising that no one brought up what has to be THE major factor in this story, the “elephant in the room.” The US has one of the highest per capita consumption of energy in the world, so the real answer is a combination approach with the emphasis on energy efficiency and reduced consumption supplemented by efforts to find cleaner energy sources. Using less energy would also mean saving more birds!

  21. Kate Huttemann says:

    Your average of 2 birds killed is misleading, because while statistics allow us to generalize to predict the big picture, they don’t speak to individual differences. As appears true for other aspects of wind projects (economic viability, environmental damage, local opposition), siting is everything. Consider an environmental impact study done at a wind farm in the Columbia River Gorge, in which bird death was predicted to be about 33 per year but which actually destroyed over 300 birds in a year.

    • Attached research says:

      Read the attached article for the detailed breakdown. Dunning’s posted that comment many times. If you have a proble with his numbers, you can read the article and see the detailed breakdown. Try reading the comments before posting, and also, I don’t see how your example works: An anectdote about predictions against the actualy doesn’t prove anything probative: read the attached research: That’s the source.

  22. Joergon says:

    I think the comparisons to the existing energy providers would be the best one to look at. If the cancer society is correct about the 100,000 human deaths due to current systems, and if that carries over to birds, a comparison to turbines, once adjusted for how many wind turbines we would need to replace the old systems and so on, would be most useful.

    It seems like it’s easy for those who use this argument to dismiss the stats on predation, glass buildings etc as irrelevant to this topic, but if the facts turn out to show that turbines would cause less bird deaths than say coal power stations for the same amount of power created, that seems to be the strongest argument.

    I would love to see an analysis of this, I am going to try and find some hard facts.

    Thank you for the interesting article.