How significant is bird and bat mortality due to wind turbines?

Last update: January 4, 2014

Wind turbines are often criticized for killing birds and bats.  Fights against siting wind turbines in bird migration corridors or in bird habitat are frequent.  Highly inflammatory language is used by anti-wind energy advocates such as ‘bird mincer’, ‘bird blender’ and ‘eagle killers’.  Outlandish numbers of deaths are often attributed to them.

How significant is the mortality of wind turbines upon birds and bats?

Short Answer:

Replacing all fossil fuel generation with wind turbines world wide would save tens of million birds lives annually.  In the USA, the best numbers show that roughly one in 86,000 birds are killed annually by wind energy. Bats are put at much more significant risk from fossil fuel and other human impacts than by wind turbines.  Displacement of fossil fuel generation makes wind a strong net benefit to birds and bats. Global warming and pollution are the threats; wind power is part of the solution, not a problem.

Long Answer:

Overall, wind energy has the least impact on wildlife of any form of energy generation with the possible exception of solar.


Every other form of generation has at some point in its lifecycle the possibility of:

  • Large scale, population-level mortality and/or habitat destruction Population(s) decline and/or biodiversity is reduced
  • A threat to species survival regionally
  • Biologically significant mortality or reduction in endangered or threatenedspecies


  • Limited, but locally to regionally important mortality and/or habitat destruction, with limited population-level effects
  • Any biodiversity declines would be local to regional only
  • No threat to species survival, but demonstrated effects to physiologyand/or behavior of exposed individuals
  • Incidental mortality and/or incidental habitat destruction of endangered or threatened species

Wind energy at worst has only the possibility of:

  • Limited and local mortality and/or habitat destruction, with no population- level effects
  • Biodiversity declines are unlikely
  • Endangered or threatened species may be exposed, but mortality unlikely

This is according to the most recent of two multi-energy source studies of wildlife mortality, Comparison Of Reported Effects And Risks To Vertebrate Wildlife From Six Electricity Generation Types In The New York/New England Region, prepared for the New York State Energy Research And Development Authority in 2009.[15]

Further, a recent assessment by the International Union for the Conservation of Nature (IUCN), the organisation that produces the Red List of Threatened Species makes it clear that up to 50% of bird species as well as many other categories of wildlife are at risk of extinction from global warming.[22]

These are the big threats.

What about birds specifically?

Birds are killed as a result of human impacts in large numbers every year. The biggest human-related causes of deaths annually are[1], [2]:

  • Lighted window impacts – 97 to 976 million
  • Predatory house cats – 500 million or more
  • High-tension wire impacts – up to 174 million or more
  • Pesticides – 72 million and possibly many more
  • Car impacts – 60 million

Even these very large numbers are relatively small compared to the threat of habitat loss from acid rain from burning coal, open-pit mining for coal, mountain-top removal mining for coal and pollution.[9

These numbers are also very small compared to the 100-200 billion birds on the planet. [16]  Adding all of the anthropogenic-impact causes of death above together might see 1.5 billion bird deaths, or 0.75% to 1.5% of the total.  Unfortunate, but not species threatening except in very specific circumstances.

Wind turbines have been added to the list of bird killers in recent years.  This is not because they kill significant numbers of birds; the worst cases has a handful of birds per turbine per year.  According to the best impartial sources, they kill perhaps 234,000 birds (median number) annually in the USA.  Of course, numbers of wind turbines are increasing, but so is siting sensitivity and mitigations (see below).  Compared to the roughly 2 billion from other sources, this cannot be considered significant.[1]  Even doubling or tripling the number of mortalities still makes wind turbines a very small contributor to avian fatalities.

A recent in depth study of avian mortality finds only 1.33 birds per turbine per year as the mean of deaths worldwide.[18] This is much smaller than critics state and still much smaller than deaths due to fossil fuel generation, but still something worth improving upon.  Of specific note in this study is the lack of any correlation between predictions of avian mortality at wind farm sites and actual mortality. It is also worth noting that this is at the low end of the scale of counts of wind turbine avian mortality, so should be taken as a point on the continuum as much as higher numbers are.

A very recent study was published in December of 2013 showed a reasonable mean of 234,000 birds killed by collisions with wind turbines annually in the USA, with bounds of 140,000 and 328,000. [24] Given the range of other studies from 30,000 to Smallwood’s high-end of 573,000 (calculated by taking 73 professionally executed empirical studies which had already been adjusted upward and adjusting them upwards further in one or more of four ways) [25], this seems like a much more likely number than both high-ball and lowball estimates. At those numbers, and looking at the estimated number of 20 billion birds in the USA after nesting, the median represents one in 86,000 birds in the USA killed annually by wind energy. With improvements in siting and mitigation, increasing wind generation to 30% of US demand would likely result in somewhere in the one in 10,000 birds killed by wind energy. Outside of endangered species, this is not significant.

Also worth noting is this recent peer-reviewed study from Canada, which concluded:

[T]hese values are likely much lower than those from collisions with some other anthropogenic sources such as windows, vehicles, or towers, or habitat loss due to many other forms of development. Species composition data suggest that < 0.2% of the population of any species is currently affected by mortality or displacement from wind turbine development. Therefore, population level impacts are unlikely, provided that highly sensitive or rare habitats, as well as concentration areas for species at risk, are avoided. [23]

Here’s a Canadian specific table for perspective. Cats kill 10,000 times the birds that wind farms do, house windows 1500 times the birds and pesticides 150 times the birds.
Screen Shot 2014-01-04 at 12.39.36 PM

It’s worth noting that while some wind farms kill a few birds per wind turbine per year, many wind farms kill almost no birds or actually no birds per year

However, there has been a noticeable absence or low frequency of avian deaths at other wind farms. Kerlinger (1997) conducted a five-month survey at the Searsburg, Vermont Wind Energy Facility and found no fatalities. Lubbers (1988) surveyed eighteen 300 kW wind turbines in Oosterbierum, Denmark, and found only 3 fatalities over 75 days, or less than 0.8 per turbine per year. Marsh (2007) found a bird casualty rate of 0.22 birds per turbine year after monitoring 964 turbines across 26 wind farms in Northern Spain. Rigorous observation of a 22-turbine wind farm in Wales documented that it has killed no birds, and researchers found a shift in bird activity to a neighboring area (Lowther, 1998). [14]

Wind turbines have tended to kill larger birds such as raptors and vultures in slightly higher numbers.  This is important as there are generally fewer of the larger birds and in the case of raptors they are an apex predator.  Threatening populations of these birds has been a concern, especially in the Altamont Pass, which is a raptor migration route.  However, bird deaths per turbine have dropped off their in recent years with the elimination of older, lattice-tower turbines that were used as roosts by raptors and significant attention to improving siting.  Attention to siting in larger bird migration routes is reasonable, as is attention to habitant for species in threat of extinction. This short documentary gives a good balanced view of ongoing efforts at Altamont Pass.

Raptors have been in the news recently as the US is considering allowing single digit takes of eagles by wind farms for periods of up to 30 years. This is reasonable as eagles are not endangered.  There are some outliers and interesting points related to this as always. The Osage Tribe is fighting wind farms on their land and asserting that it’s their reverence for eagles for the basis for their fight, but they clearly state in their lawsuits and internal press that they are worried oil and gas extraction from their lands would be hindered by wind farm development. As eagles populations are much more threatened by global warming and pollution than wind farms, from the outside this can only be described as hypocritical.  Further, evidence out of Australia where researchers spent two and a half years observing eagles at wind farms found that two different species very clearly avoided wind turbines. And of course, raptor populations are stable or rebounding at present in many cases.

And a recent UK study on a 10 bird species near wind turbines found that construction disrupted populations slightly, but that operation did not cause any challenges for the majority of species, aided one species and only had a minor negative impact on numbers of one type of bird.[11]

In general, song birds migrate at 2000-4000 feet, well above the level of wind turbines. Sea birds have been shown to avoid wind turbines based on radar and thermal imaging studies; one study found that millions of sea birds migrated past an offshore wind farm annually, and only two were killed. [19] This radar mapping of north and south migrations of migratory seabirds is very illustrative of what sea birds do:

Image courtesy of NERI report "Final results of bird studies at the offshore wind farms at Nysted and Horns Rev, Denmark

Image courtesy of NERI report “Final results of bird studies at the offshore wind farms at Nysted and Horns Rev, Denmark [21]

It is also worth considering the alternative: more fossil fuel generation.  Wind farms and nuclear power stations are responsible each for between 0.3 and 0.4 fatalities per gigawatt-hour (GWh) of electricity while fossil-fueled power stations are responsible for about 5.2 fatalities per GWh.[14] (Coincidentally, human fatalities per TWh of electricity are roughly 0.4 for nuclear and wind, and roughly 5 for coal according to one study; the very similar ratios between human and avian mortality are striking).

This graph from the energy policy report that established relative bird deaths for nuclear, wind and fossil fuel is telling:  estimated world-wide avian mortalities in 2006.[14]


According to Worldwide electricity production from renewable energy sources, 2011 Edition, [17] fossil fuels generated 14,264.4 TWh of electricity in 2010.  Assuming this number and the ratio of mortality, replacing all fossil fuel generation with wind energy would save the lives of roughly 70 MILLION BIRDS ANNUALLY.

Mitigations for bird deaths continue to be pursued, including radar assessment of bird density causing wind farm feathering, painting the blades purple to avoid attracting birds during the day and avoiding steady white lights that attract insects and birds at night.[7], [8]

What about bats?

Bats are also killed by wind turbines, once again a few bats per turbine per year in areas where bats are common, but rarely if ever through direct collision. University of Calgary studies show that bats are very able to avoid moving wind turbine blades through echo-location. However, they suffer from barotrauma — a significant pressure difference that disrupts their hearts and lungs — when they fly close behind the blades.[10], [12]

Bat populations are not threatened by wind turbines. Bats are put at risk by many of the same things that put birds at risk: pesticides and habitat destruction among them.

White-nose syndrome is the biggest threat to bats right now in the USA. It has caused 300,000 deaths in one cave in the US alone, much more than the total bat deaths related to wind turbines.[2], [13]

The industry and governmental agencies still take bat mortality due to wind turbines seriously.  Where wind turbines impact sensitive populations, there have been interventions as significant as nightly shut downs of the entire wind turbine farm due to a single bat death.[3]  There is ongoing work to reduce bat deaths through radar, ultrasonic and higher-blade startup speeds.[4], [5]

[9] Wind Energy: Do wind turbines have an impact on aquifers?
[10] Mike Barnard’s answer to Why are bats not better able to avoid wind turbines?


[23] Zimmerling, J. R., A. C. Pomeroy, M. V. d’Entremont, and C. M. Francis. 2013. Canadian estimate of bird mortality due to collisions and direct habitat loss associated with wind turbine developments. Avian Conservation and Ecology 8(2): 10.

[24] Estimates of bird collision mortality at wind facilities in the contiguous United States, Scott R. Loss, Tom Will, Peter P. Marra, Biological Conservation, Volume 168, December 2013, Pages 201–209,

[25] Comparing bird and bat fatality-rate estimates among North American wind-energy projects, K. Shawn Smallwood, Wildlife Society Bulletin, Volume 37, Issue 1, pages 19–33, March 2013, DOI: 10.1002/wsb.260,

A subset of this material was published on RenewEconomy here:


  1. Mike one question, are you paid for this avocation of wind energy?

    1. Unequivocally no. I receive no money of any kind from any person or organization for blogging or correcting disinformation online.

      This is a fairly typical claim of anti-wind campaigners who are unable to provide referenced, peer-reviewed support for their a-factual positions, so they attack the messenger instead.

      And I believe you meant ‘advocacy’.

  2. [...] Wind farms average 1-2 bird deaths per turbine per year around the world. Every study, every energy utility and every major birding organization in the world agrees that wind energy is one of the absolute best choices for birds and wildlife in general. [...]

  3. [...] Every study, every energy utility and every major birding organization in the world agrees that wind energy is one of the absolute best choices for birds and wildlife in general.…..  Crichton’s research indicates that  Ms Laurie is significantly responsible for the [...]

  4. [...] Wind farms average 1-2 bird deaths per turbine per year around the world. Every study, every energy utility and every major birding organization in the world agrees that wind energy is one of the absolute best choices for birds and wildlife in general. [...]

  5. [...] Every study, every energy utility and every major birding organization in the world agrees that wind energy is one of the absolute best choices for birds and wildlife in general.…..  Crichton’s research indicates that  Ms Laurie is significantly responsible for the [...]

  6. [...] Wind farms average 1-2 bird deaths per turbine per year around the world. Every study, every energy utility and every major birding organization in the world agrees that wind energy is one of the absolute best choices for birds and wildlife in general. [...]

  7. Hi Mike,
    Would you care to comment on this story?

    Your own thoughts please, not a regurgitated AWEA press release, if that’s OK with you.
    And please remember we’re talking about endangered raptors, not sparrows.

    1. An unfortunately deeply unbalanced article from AP that’s being picked up by other news agencies.

      To pick apart merely one of the many problems, the 573,000 number is a huge outlier from the set of credible numbers. The lowest end of the range is 30,000 per year and the consensus of studies and assessment is in the 100,000-200,000 range and the previous high-water mark outlier was under 500,000.

      So why is this number being touted, and what is it’s provenance? I pulled the entire set of articles from the journal, including the one this number is from to find out.

      Smallwood, the researcher is an accredited ornithologist with a history of research related to wind energy and avian mortality, specifically in the unfortunate Altamont area. So far so good.

      Smallwood’s methodology is to take the 71 avian mortality studies he was able to get his hands on and based on his own research and published studies, adjust the all of the numbers upwards in one or more of four different ways: radius of search, scavenger take, searchability of terrain and length of time carcasses would persist. All well and good, you would think, except that he is basically taking exception to all of the approaches to avian mortality counts and all of the prior adjustments. His publication history shows that he virtually always publishes alone.

      In other words, this researcher is a bit of an iconoclast who thinks everyone else is wrong not just in one way, but multiple ways. His paper is an extensive re-writing of empirical and carefully constructed avian mortality studies by teams of careful researchers before him.

      And while he gives a range of mortality for bats, he gives no range or margin of error for his adjusted numbers for birds.

      Given that his results are so much larger than any other numbers produced is one reason to view them with suspicion. Given that he has produced these numbers alone based on his own research predominantly is another reason to consider them unreliable.

      It’s also shoddy journalism to pretend that this is a particularly significant number in terms of bird populations outside of endangered or at risk species. There are perhaps 200 billion birds world wide at any given point, and humans kill up to 1 billion of them annually via domesticated cats, traffic kill, lighted windows, pesticides and etc. When significance of bird deaths typically starts in the 10s of millions, <1 million starts to gain perspective.

      The real threat to bird populations is pollution and global warming, and wind energy displaces greenhouse gases on almost exactly a one-for-one basis with every MWh of electricity produced. Wind energy is much better for wildlife than any other utility-scale form of generation.

      Siting is important, but unbalanced articles such as the above are not helpful to discussions.

      As for eagles specifically, what applies in general to bird populations applies to eagles as well. Wind energy is good for them, good for their habitat and goo for their prey in general; some specific eagles die when they are hit by wind turbine blades. Comparatively, fossil fuel generation is bad for eagles, bad for their habitat and bad for their prey; some specific eagles die due to fossil fuel related impacts. Given that a MWh of wind energy displaces almost exactly 100% of the pollution and CO2e of a MWh of fossil fuel generation, the moral calculus says it's very reasonable to allow wind energy to do exactly when every other industry that knows it might impact eagles to do; establish a guideline, mitigations and targets that minimize eagle impacts and provide a known and stable framework for an individual wind farm.

      That's why every major birding and wildlife organization strongly supports wind energy and has policies and statements that say so, as well as lots of effort with other organizations to get smart siting and operational mitigations in place.

      As wind farms are the only source of generation that is required to monitor avian mortality, this is just more of the same imbalance really and the question is why the same scrutiny and unbalanced reporting isn't applied to those industries.

      I'll be adding the material on Smallwood to the post you commented on by the way. It's the sort of trashy meme that anti-wind types throw around without looking at closely, just because it seems big and scary.

      As for the rest, there isn't actually much of a story there that hasn't been firmly put in context by others, including the AWEA coverage you disparage.

      1. So, you start with an ad hominem attack against the researcher whose study you don’t like, before going on to say his numbers are statistically irrelevant anyway. Personally, I disagree with the idea that, because there is already a lot of evil in the world, a little bit more will do no harm; this seems to be the substance of your argument in this case. I think we can agree to differ here.

        Next you accuse the WP of shoddy journalism, “… to pretend that this is a particularly significant number in terms of bird populations outside of endangered or at risk species.” May I point out that endangered or at risk species comprised the entire focus of this article. So what is your point?

        Next we have the familiar refrain: The biggest threat to birds is climate change and wind power reduces CO2 emissions, thereby mitigating climate change.

        Can you quantify the effect of climate change on bird populations? No. Can you quantify the effect of wind power’s CO2 savings on climate change? No. And yet it is deemed acceptable for (a highly quantifiable) number of birds to be killed because of some utterly unquantifiable benefit that may or may not accrue in the future. I call that tenuous.

        Then you appear to say that, because other methods of generation kill birds, it’s only fair that wind-power should be able to kill its share too? (sorry – I had difficulty following your writing at that point., so maybe you were saying something else).

        I am aware that organisations such as the Royal Society for the Protection of Birds strongly support wind power. I am also aware of the existence of, up until recently, RSPB Energy, a branch of this organisation dedicated to making money out of the sale of “ecological” electricity tariffs. Forgive me but, when I see conflicts of interest like this, I come over all cynical.

        The main point of the WP article was not that take permits are bad, but that wind power companies who kill endangered raptors without a permit appear not to be prosecuted. As well as being an injustice, this undermines the whole idea of a take permit. The WP article cites a particular company that cannot even apply for a take permit because it already kills too many eagles. And so the unauthorised killing continues, and the administration turns a blind eye.

        I’m glad you think all of this is OK, but to me it looks like a system that is not fit for purpose.

    2. This is a worthwhile article to read as well. Much more balanced.

      1. Much more balanced? I don’t think so.

        This article, on a wind industry website boils down quite quickly to the basic idea that because bald eagles are killed by this human activity and that human activity, it is only fair that wind turbines should be allowed to kill their share of eagles too. Do tell me if I’ve got it wrong.

        And as for hunting, we have that here too: a bunch of incompetents leaving a trail of injured and dying animals behind them. And I hear from my friend, who was a hunting guide in the States for a while, that it is a hundred times worse there. The article is really grasping at straws to use this despicable practice as some sort of justification for the killing of raptors by wind turbines.

        And the last word of the article – that eagles that fly into wind turbines should be tested for impairment by lead poisoning. I can predict the hoped for outcome already: every eagle in the States probably has some degree of lead in its body. Therefore all eagles that fly into wind turbines did so because of that. Therefore it wasn’t the turbine’s fault. I invite you to take a look at this video: Do you think this vulture was impaired? Or is it possible that these birds simply do not understand the concept of a rotating blade whose tip is travelling at over 50 m/s?

  8. AeroFox · · Reply

    I don’t doubt the stats here, have reviewed them myself. No one here appears to be denying causality in avian mortality, but, to clean the grist from the “anti-wind” mill (Jim Weigand & Dick Smallwood-“avian experts?”). I did catch the throw-down on SciAM blog from last year.

    Can wind turbines be “avian friendly” at the equipment level? This is a STEM topic IMHO.
    Firstly, and semantically speaking (pun intended), I don’t see wind turbines and golden eagles hanging out at sundown drinking pale ale. So much for avian friendliness.
    And onto “avian deterrence”. Perhaps the change in semantics makes a difference in how we approach this issue or non-issue?
    1. How do we modify the equipment to deter avians, primarily, eagle species (and other endangered species) , regardless of migratory path, nesting, breeding and hunting grounds? In other words, remove all doubt, and negative fuel for the “AW’s”.

    It is intuitively tough to digest that a majestic apex raptor like the golden eagle that can spot fish through murky water from hundreds of yards above, that can target rodents and jack-rabbits from literally a mile away, has not adapted to IWT’s. Obviously the growth rate of Big Wind has been to quick for eagle hunting adaptation. Eagles and other raptor species see in ultraviolet and infrared light spectrums incapable of detection by the human eye. They also migrate and hunt by infrasound signatures as well (many machines have an infrasound signature-not just IWT’s). Two items that seem to be removed from discussion. As technologists, we should be focused on those 2 key issues to resolve this, so the human species can move forward, without perturbance from the 2 “avian experts” that don’t care to stay debunked. And at least 1 is paid very well to keep mouthing off and trolling every blog from East San Diego County, Altamont to Falmouth. He’s bi-coastal.

    If you (rhetorically speaking) were an avian expert truly concerned, wouldn’t and shouldn’t the items posited, be the central focus of any argument you may have regarding co-existence of IWT’s and eagle species?

    I shall find a new avian expert, maybe I’ll hire Dr. Pussy Breastwell for future studies, to complement Dick Smallwood. (j/k)

  9. […] bird kills at wind farms.  Additionally, wind power generation poses much less risk to birds than other forms of energy generation.  It’s estimated that, in 2006, fossil-fuel power plants were responsible for 14.5 million bird […]

  10. There is no doubt that wind power is a good thing. The bad thing is that the wrong turbine design is being mass produced and installed, making conversions to a bird-friendly design too expensive. Granting wind farms a permit to kill the birds will not help to improve the turbines design.

    1. Ummmm…. no.

      If we agree that the biggest threats to bird species are global warming, habitat loss and pollution, and we can agree that humans will continue to need electricity that is economically viable, then we can state the following pretty unequivocally.

      Current wind turbines are the most effective form of wind generation by far. No other form of wind generation has proven itself to be reliable, scalable or cost effective despite decades of studies, prototypes and attempts.

      Current wind turbines kill a fraction of the birds that fossil fuel generation does directly through pollution and habitat destruction and less directly through global warming. Every MWh of wind energy generated displaces one MWh of fossil fuel generation and abates close to 100% of the negative impacts of that fossil fuel generation.

      Don’t buy the hype from people claiming that vertical axis wind turbines or shrouded turbines are better, cheaper or safer for birds. They aren’t economically viable, their claims have been disproven time and again, and there just aren’t any major farms of them at the same scale as wind turbines so there is absolutely no data to prove their assertion that they are safer for birds. It’s just an attempt by them to sell their product.

      So the next time someone says current wind turbines are the wrong type of wind generator, please correct them. It’s completely and utterly false.

  11. […] Barnard on Wind web site (creator: Mike Barnard).  More specifically they referenced the article: How significant is bird and bat mortality due to wind turbines?  This article, along with its extensive list of references, contains a wealth of information for […]

  12. AeroFox · · Reply

    Well, significant in terms of cost of fines, legal fees, public relations, land lost revenue from curtailment. $1Million for 14 Eagles + 149 other non-endangered, but protected species.

    Will there be fines for building owners, transmission line operators., or does this stop at some point.

    1. Hard to say. Definitely some people already saying “I told you so” to developer of that site right now.

      And definitely not the most effective PR strategy for the wind industry.

      1. AeroFox · ·

        I meant “and lost revenues” in previous reply. Obviously, siting locations that are MBTA zones will require hire insurande and lenders may charge points so debt service coverage ratios arent affected. Who knows?
        Loss of good sites, like protected areas could reduce the usable site supply-an unintended consequence. But the solution is technical. Somewhere between UV lighting, thin film solar cells and a propeller-a team is working on the solution anticipating this recent action.

  13. AeroFox · · Reply

    Found this to be a good read. Effort is being put forward. There are technical solutions to this problem. But I have to disagree with recent 30 year take rulings for “accidental deaths”. Even though they (WT’s)are for the benefit of all species, one lawsuit begats another and another and then costs rise…

  14. Vesper · · Reply

    Sorry this is old but it needed some info supporting bats.

    Wind energy is having an impact on bats at the landscape level. Specifically, three species of long distance migratory bats (the hoary, silver-haired, and red bat) are all being impacted at a rate that when coupled with their low reproduction rate, will see declines.

    Protecting bats is worth the effort and if industry doesn’t see the need to be proactive, policy will need to be developed and at that point we can all look back and say “we should have done something then”.

    1. Please provide references. Assertions without solid citations are difficult to accept.

      Glad to review solid material and help push for mitigations.

      1. Vesper · ·

        Here are some supporting pubs:

        fatality estimates-
        Smallwood, K.S., 2013. Comparing bird and bat fatality-rate estimates among North
        American wind-energy projects. Wildlife Soc. B. 37, 19–33.

        Hayes 2013 (sorry, I couldn’t access publication but here is the pre-pub)

        Support for wind growth-
        American Wind Energy Association, 2013. U.S. Wind Industry Third Quarter 2013 Market Report Executive Summary. Washington, D.C. .

        Canadian National Energy Board. 2011. Canada’s Energy Future: Energy Supply and Demand Projections to 2035 – Emerging Fuels and Energy Efficiency Highlights. .

        U.S. Department of Energy (DOE), 2008. 20% Wind energy by 2030: increasing wind energy’s contribution to U.S. electricity supply. U.S. Department of Energy, Office of Scientific and Technical Information, Oak Ridge, Tennessee. (accessed November 2013).

        U.S. Department of Energy (DOE), 2013. 2012 Wind technologies market report. U.S. Department of Energy, Oak Ridge, Tennessee. (accessed November 2013).

        Support for bat/wind concerns-
        Kunz, T., E. Arnett, W. Erickson, A. Hoar, G. Johnson, R. Larkin, M.D. Strickland, R. Thresher, and M. Tuttle. 2007. Ecological impacts of wind energy development on bats: questions, research needs, and hypotheses. Frontiers of Ecology and the Environment 5(6):315-324.

        Racey, P., and A. Entwistle. 2000. Life-history and reproductive strategies of bats. Reproductive biology of bats, 363-414.

        Take a look at the estimates from Smallwood and Hayes. These are from 2012. Also, I could not provide but there is text in Bat Evolution, Ecology, and Conservation 2013, pp 435-456 by Arnett “Impacts of Wind Energy Development on Bats:” that has some lower estimates but still defines the magnitude of the issue. It is harder to compare to the others as it looks at regions across the US.

        The first two (Smallwood and Hayes) are based on MW production. Add that to cumulative growth and NO protection form USFWS “VOLUNTARY” land based Wind Energy Guidelines and you can start to see a scary picture for these bats. Bats reproduce slowly and live long to accommodate this life history. Fatalities to adults in this type of life history are hard to overcome and potentially impossible when we look 5-30 years down the road (dependent on where wind energy development occurs and at what rate.

        The other publications should help provide info on life history of bats and expected wind energy growth. Also, the current administration strongly supports this growth.

        I’m not against wind energy. I am against the extirpation of bats, especially when these are some of the few that are not susceptible to White-Nose Syndrome.

        Thanks for the opportunity to comment and sorry it is so long.

      2. Vesper, thanks for the extensive references. I’ll dig through then over the next while to assess them and clarify the concern.

        I wouldn’t over-rely on Smallwood by the way. His work on birds is a significant outlier in the research, about 150k annually above the next highest estimate, and 2.5 times the median in a more robust study published late in 2013. I haven’t paid as much attention to his bat numbers as his bird numbers, but I would have the same concern until I could determine otherwise.

        I completely agree that species level threats, if they exist, are to be avoided or mitigated. You’ve provided a good set of reading for me to clarify where the concern really lies. Thanks.

      3. Vesper · ·


        Smallwood’s estimates have been a target of criticism. They are extremely high compared to some US Fish and Wildlife supported work (I think the author is Loss-2013). He is the high end for bats also so he should be considered as such.

        I think his methodologies are solid but the variables with bats, specifically surrounding long distance migratory bats and bat fatality carcass surveys at wind fatalities, can really cloud any of specifics enough to make “fact” and “guess” become closer to the same.

        None-the-less, I think that if we were talking about three bird species instead of three bat species, this topic would be a much larger concern. That is a tough pill to swallow for me.

        Once again, thanks for the opportunity to voice my feelings and try my best to support them.

      4. I know what you mean about the comparative concern. Human’s inability to love huge swathes of ecosystem that aren’t cute definitely clouds the discussion.

        Just back from vacation and have to do more of my day job, but your references are high on my list of things to get to. Thanks again.

  15. […] to be much more difficult to perceive and avoid than any wind turbine blade for birds. The best evidence is that many species of birds including seabirds and many raptors simply adapt to wind farms and […]

  16. AeroFox · · Reply

    Worth re-posting. Any shill for the carbon industry is worth pointing out.

  17. KJK · · Reply

    Respectfully Mr. Barnhard, you and the people who did the studies apparently don’t live near a wind tower farm. There is no way that a wind farm such as the one a couple miles away from our home, each having 80 foot blades can be “beneficial” to bald eagles and bats. I’ve seen a dramatic reduction in our eagle population over the past year that the nearest wind farm has been around. I’m sure any study can be made to look to the advantage of the wind farms. Unless those doing your studies actually camp-out for several weeks 24 /7 under each wind tower, (that would involve about 200 – 300 people) and honestly record the results, I would not believe anything reported by your “researchers”. Just because one wind tower doesn’t kill an eagle at any particular studied time, doesn’t mean that another wind tower five miles away isn’t. Also, how does anyone know that there were eagles in your study area in the first place. In the case of our area, there has been an abundant amount of eagles for the past 30 years. Over the past five years that the two area wind farms have been around, the eagle population has practically vanished. One last thought — it doesn’t really matter whether only one eagle is killed by the wind towers, or 2000. Our national bird is a protected species, and it is illegal to kill them. Pipelines carrying oil don’t sock eagles in the face, and flip them across the countryside. I am appalled that it was suggested in the comments above that the eagles flew into the wind towers, so therefore we can’t blame the towers. YES, WE MOST CERTAINLY CAN BLAME THE TOWERS. If the towers weren’t in the birds’ way with huge spinning blades, the birds could fly freely in the wide open spaces with virtually no other in flight threat (except maybe planes).

    1. So instead of researchers with credentials, careers and verifiable histories who publish in peer-reviewed journals we’re expected to believe a random commenter on the internet who has no expertise or methodology that can be verified.

      Would you expect that from your doctor, lawyer or the engineer who designed a bridge you were driving across?

  18. Henk Hutting · · Reply

    I think the best indirect proof that wind turbines are no big problem for birds is given by the fact that the official policy of organizations like the Royal Society for the Protection of Birds ( ) is to embrace wind energy, provided proper environmental effect studies are performed.

Be nice, be respectful, be relevant.

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