Growing “Swept Area” Of Annihilation…Study Points To Wind Turbines’ Barotraumatic Mayhem Of Bats

As wind turbines increase in size and scale, so do their deadliness to wildlife and hazards to human health.

Today’s modern wind turbines now soar to heights of up to over 200 meters, can have outputs of well over 5 MW, and blade tip speeds of over 300 kilometers per hour, thus making them especially lethal to avian wildlife, and hazardous for human health through infrasound.

bat barotrauma

Source:, Erin F. Baerwald et al.

21,000 square meters of “swept area” of annihilation

To give an idea of their scale, Danish company Vestas, for example, offers an 8-MW offshore turbine with a total height of 220 meters that is equipped with a monster rotor diameter of 164 meters. The result: horrendous blade speeds and pressure gradients. Flying wildlife stand no chance. Worse is the growing size of the hazardous swept area.

Vestas boasts that its V164-8.0 MW® turbine has a swept area of more than 21,000 square meters, which is “equivalent to almost three football pitches“. Vestas bellows: “When it comes to profitability, the bigger the swept area the bigger the revenue.”

Unfortunately for birds and other wildlife it is also: The bigger the swept area, also the bigger the wildlife annihilation area. But wildlife be damned.

Huge number of fatalities

Wildlife fatalities from wind turbines are poorly documented and mostly unknown. Estimates are on the low side and thought to be much higher, as the industry attempts to play down their real danger.

Birds, bats and other animals can be killed by turbines in any one of three ways: 1) through loss of their habitat due to the disruption of a vast installation area, 2) direct impact with high speed moving blades (birds) and 3) from barotrauma, where bats are the primary victims.

The most sinister of the three is barotrauma, which is a common way bats are killed by wind turbines.

Study shows mayhem

An article published at by Erin F. Baerwald et al of the University of Calgary confirms the violent deaths that bats suffer from wind turbines. Bats do not even need to come into contact with the moving blades. It is enough for them to be close to the end of a moving blade to become victims of barotrauma. As the turbine’s blade slices by at 300 km/hr, the negative pressure in the blade’s wake causes the air in the bats’ lungs to expand and incur lethal injury.

Barotrauma typically occurs when an organism is exposed to a significant change in ambient pressure, such as when a scuba diver, a free-diver or an airplane passenger ascends or descends, or during uncontrolled decompression of a pressure vessel.

The article writes:

The decompression hypothesis proposes bats are killed by barotrauma caused by rapid pressure reduction near moving turbine blades [1,4,5]. Barotrauma involves tissue damage to air-containing structures caused by rapid or excessive pressure change; pulmonary barotrauma is lung damage due to expansion of air in the lungs that is not accommodated by exhalation.”

Moving turbine blades create zones of low pressure as the air flows over them. Animals entering these sudden low pressure zones may suffer barotrauma; article writes:

Pressure differences as small as 4.4 kPa are lethal to Norway rats Rattus norvegicus) [6]. The greatest pressure differential at wind turbines occurs in the blade tip vortices which, as with airplane wings, are shed downwind from the tips of the moving blades [7]. The pressure drop in the vortex increases with tip speed, which in modern turbines turning at top speed varies from 55 to 80 m/s. This results in pressure drops in the range of 5–10 kPa (P. Moriarty, personal communication), levels sufficient to cause serious damage to various mammals [6].” […]

Even if echolocation allows bats to detect and avoid turbine blades, they may be incapacitated or killed by internal injuries caused by rapid pressure reductions they cannot detect.”

188 dead bats examined

Baerwald and her team examined 188 dead bats killed by a wind turbine facility in southwestern Alberta:

Of 188 bats killed at turbines the previous night, 87 had no external injury that would have been fatal, for example broken wings or lacerations (Table 1). Of 75 fresh bats we necropsied in the field, 32 had obvious external injuries, but 69 had haemorrhaging in the thoracic and/or abdominal cavities (Table 1). Twenty-six (34%) individuals had internal haemorrhaging and external injuries, whereas 43 (57%) had internal haemorrhaging but no external injuries. Only six (8%) bats had an external injury but no internal haemorrhaging.

Among 18 carcasses examined with a dissecting microscope, ten had traumatic injuries. Eleven bats had a haemothorax, seven of which could not be explained by a traumatic event. Ten bats had small bullae — air-filled bubbles caused by rupture of alveolar walls — visible on the lung surface (Figure 1A). All 17 bats examined histologically had lesions in the lungs consistent with barotrauma (Table 1), with pulmonary haemorrhage, congestion, edema, lung collapse and bullae being present in various proportions (Figure 1). In 15 (88%), the main lesion was pulmonary haemorrhage, which in most cases was most severe around the bronchi and large vessels.”

In summary, the wind turbines are extremely lethal to wildlife on a scale so horrendous and embarrassing that it is being kept out of the public’s eye. What’s worse is that these turbines, and the growing swept areas of annihilation they bring with them, have been installed by the thousands and plans are being made to install many thousands more – many in natural areas. Wildlife will have no chance.

This is all endorsed by Greenpeace and the WWF.


24 responses to “Growing “Swept Area” Of Annihilation…Study Points To Wind Turbines’ Barotraumatic Mayhem Of Bats”

  1. Anything is possible

    Truth : Irrational fear of climate change is killing bats.

    My predicted MSM headline : “Climate change is killing bats”

    1. DirkH

      You got the job.

    2. Henning Nielsen

      As the English say: “Bats in the belfry.”

  2. lance

    What is interesting is many years ago CTV or some media outlet ‘briefly’ talked about the decline in bats down in the Pincher Creek area, then….silence…they stated the U of Calgary was studying the issue. You talk to locals and the bats are just disappearing down there. Yet, more and more wind mills show up down there, and built every summer. Yet, ‘crickets’ from the media about the birds/bats/raptors. Of course, have a few ducks land in a tailings pond and the world hears about it

  3. Erin Baerwald

    Hi there,

    You seem to be discussing the manuscript I wrote and published in 2008, but have some errors in your piece.

    1) Bats seem to be killed most frequently by being struck by blades. Yes, they can also be killed or injured via barotrauma, but it is likely a much smaller threat than being struck. Check out the follow-up studies like this

    2) Yes, the 188 bats were bats that were freshly killed (i.e. picked up the morning after dying), but we found these throughout our field season (mid-July to mid-September, not in one night.

    3) Bats’ lungs don’t actually burst, it’s not nearly that dramatic…the small alveoli and capillaries can rupture, but not the lungs themselves

    hope this helps clear up the science 🙂

    Erin Baerwald
    Pls note UW-Madison article points to exploding organs. “As they hit that pressure gradient, it can cause their internal organs to explode.” -PG

  4. Ed Caryl

    Another “Silent Spring”!

  5. sod

    3 bats killed every day! That is total annihilation and mayham that nobody ever saw before!!

    We should return to environmental friendly technologies like nuclear and coal immideately!

    1. AndyG55

      Yes we should. This un-controlled culling of bird and bat species by the GREEN, so-called environmental, far-left agenda should never have been tolerated.

      If the wind-turbines had to go through the same environmental hoops that REAL power supplies have to, there would be very few of them, anywhere.

      Because they are “green”, they get off basically scot-free, and the greenie/environmentalist.. JUST DON’T CARE !!

      As is obvious from your comment.

    2. Bart

      1095 per year per windmill facility. Are coal or nuclear killing at such a pace? No, they are not. Not even remotely.

      Bats are the slowest reproducing mammals of their size, owing to the fact that the mothers can only give birth to one pup per year.

    3. DirkH

      sod 3. March 2015 at 02:25 | Permalink | Reply
      “We should return to environmental friendly technologies like nuclear and coal immideately!”

      As coal and nuclear are not consuming organic matter, and are not competing with the biosphere, and coal even provides food to the biosphere after being burned, this would lead to a thriving biosphere.

      Let’s look at the pre-nuclear, pre-fossil fuel age and take a look at European forests… there weren’t many. Wood was harvested faster than it could regrow for shipping, heating, construction. Entire landscapes in Europe like the Lüneburger Heide or the Yugoslavian Karst landscape came about through deforestation.

      The Greens want us to return to this ravenous consumption of our environment.

      1. AndyG55

        “The Greens want us to return to this ravenous consumption of our environment.

        They are already raping American forests to provide wood chip for Drax electricity in England.

        This is the height of environmental hypocrisy and stupidity… courtesy, the green agenda.

  6. roger

    From Erin B’s link we find
    ‘Roughly half of the bats examined also had middle and/or inner eardrum ruptures. Drake notes that such damage would not immediately be fatal but would disorient an animal, impair its ability to navigate and hunt, and likely hasten its demise. These non-instantaneous deaths may lead to an underestimation of the true extent of bat mortality near wind farms, he adds, since injured animals may be able to fly outside the search area before dying.’

    Consider also that the entry point of a bat into the vortex would have a bearing on whether death was instantaneous or just injurious enough to allow flight and lingering death some miles away, it is difficult to credit this research as being anything other than a guess rushed out over an eight week period.

  7. Curious George

    The advantage of offshore wind turbines is that there are no pesky biologists counting dead bats and birds. I wonder if this is the main reason for offshore wind farms.

  8. Dr A. Cannara

    Indeed, windmills are not only inefficient and resource wasteful, they’re unnecessary killers of various species, including us… (deaths & injuries)

  9. BobW in NC

    …and let us not forget that the barometric “sound” makes people sick, too:

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