Can Wind Power Be Wildlife Friendly

As birds and bats migrate along windy mountain ridges—the same ridges that are optimum sites for wind turbines--new research aims to stop turbines from killing animals

  • By Joseph Caputo
  • Smithsonian.com, February 27, 2009, Subscribe
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Dr Edward Arnett and Chris Long at Casselman Wind Power Project in Pennsylvania
Dr. Edward Arnett (in the orange vest), a scientist with Bat Conservation International and his bat-finding labrador retriever accompany plant manager Chris Long at the Casselman Wind Power Project in Pennsylvania. (Iberdrola Renewables)

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Scientist Ed Arnett

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According to Edward Arnett, a scientist with Bat Conservation International, wind turbines are going to be built no matter how little we understand about bat biology. “We have an industry moving forward with or without the science,” he says. This puts researchers like Arnett under a tight deadline to work with the wind industry for a solution. Approximately 55 new wind turbine facilities were built in 2008, reports the American Wind Energy Association, 40 more than in 2007. “It’s not necessarily how science should be conducted but it’s how we have to approach what we are faced with,” Arnett says. And he is making progress.

Arnett, a program coordinator for the Bats and Wind Energy Cooperative (BWEC), a partnership between conservationists, government agencies and the wind industry, is experimenting with a bat deterring device. The latest model in development contains 16 speakers that emit ultrasound, which should jam bat echolocation and coerce a bat to change its flight course. They are now working to test the device and evaluate reduction in bat kills.

Arnett’s second solution is to increase the minimum wind speed necessary for wind turbine blades to start turning. Research shows that bats are more likely to be hit on calm nights in late summer and fall. Because this could cause a drop in a wind facility’s energy production, Arnett had trouble getting a company to sign on to study this solution. It was the world’s leading provider of wind power, Iberdrola Renewables, that finally agreed to collaborate, giving Arnett access to all 23 turbines on its Casselman Wind Power Project in Pennsylvania. According to Andy Linehan, the company’s wind permitting director, the benefits of finding a solution to the bat fatality problem outweighed the costs of producing slightly less energy. “We market ourselves as a green industry,” he says. “If we’re going to continue to take that seriously, we’ve got to continue to show it.“

The experiment was a success. By curtailing production during low wind conditions, and increasing the wind speed threshold required to jump-start the turbines, bat fatalities dropped between 56 and 92 percent. The costs to the company were small: a less than one percent overall power loss for the year. Arnett now wants to test this strategy at several more sites.

“This is a worldwide issue,” says Barclay, who is also a science advisor for BWEC. “Most of the research is being done in North America, but wind turbines are going up at an incredible rate in other parts of the world, and so the research we do here can have a potentially bigger impact.”


The wind turbines had just been put up on Backbone Mountain when Keith Lott arrived in the summer of 2003. The field technician had been hired by a wind energy consulting company to survey bird fatalities at the new Mountaineer Wind Energy Center in West Virginia. Every other week, Lott walked concentric circles around some of the facility's 44 turbines, sweeping a 200-foot radius in search of victims that had collided with the swooping blades above.

Bird surveys became standard procedure after thousands of raptors, including federally protected golden eagles, were found to be crashing into the nearly 5,000 turbines on the Altamont Pass Wind Farm, built in California during the 1970s. Lott was hired in response to concerns that wind farms on Appalachian ridges, which act as corridors for migrating songbirds and hawks, might invite similar misfortune.

To Lott’s surprise, the dead bodies surrounding the turbines weren’t birds, but bats. Lott and other surveyors found 475 bats, many broken-winged and bloodied, at the West Virginia facility that year. He and his team estimate that 2,092 bats were killed. Scientists knew that turbines posed a threat to birds, but nobody had predicted they’d be such a problem for bats.

Research at the Mountaineer Wind Energy Center helped raise awareness about bat fatalities at turbines. Five years later, it has been recognized as an international problem, with bat deaths documented in Australia, Britain and Canada. Along with deaths of endangered birds, the carnage has added another speed bump to wind power’s ability to win over environmentalists. But there is good news. Research spurred by the bat fatalities has conservationists and wind industry representatives hopeful that an effective solution will be in place within the next five to ten years.

Whether or not this time frame is good enough is still unknown. The most common species found dead around North American wind farms—the hoary bat, eastern red bat and silver-haired bat—are killed by turbines as the bats migrate between Canada and Central America. None of these species are listed as endangered, but no one knows the potential impact from thousands of deaths each year. According to Robert Barclay, a University of Calgary biologist who studies bat fatalities, the impact could be serious: females from these species give birth to only one set of twins a year, a much slower reproductive rate than birds, which may have half a dozen young a year.

Though bird deaths prompted wind energy companies to start monitoring turbines' impact on wildlife, it turns out that Altamont Pass was an exception. Bird fatalities are approximately 2 per turbine per year, according to the National Wind Coordinating Committee, compared to the 21 to 70 bats killed per turbine per year along their Eastern migration routes.

Why do so many bats fall victim to wind turbines? With good eyesight and the ability to echolocate, or detect their surroundings through sound, it seems that they ought notice the potential danger. Some insight came last year from Erin Baerwald, a graduate student working with Barclay in Canada. She noticed that half of the bats scattered around turbines do not have any visible injuries. After conducting autopsies, she found that they all showed evidence of "barotrauma." That is, their lungs had burst due to a sudden drop in air pressure.

Baerwald suggests that bats are attracted to the turbines. “In order to be killed [by barotrauma], the bats have to be pretty close to the blades,” she says. “The zone is a meter or two around.” Why the migrating bats would be drawn towards the turbines is still a mystery. Scientists hypothesize that bats may see turbines as tall trees or roosting sites.

According to Edward Arnett, a scientist with Bat Conservation International, wind turbines are going to be built no matter how little we understand about bat biology. “We have an industry moving forward with or without the science,” he says. This puts researchers like Arnett under a tight deadline to work with the wind industry for a solution. Approximately 55 new wind turbine facilities were built in 2008, reports the American Wind Energy Association, 40 more than in 2007. “It’s not necessarily how science should be conducted but it’s how we have to approach what we are faced with,” Arnett says. And he is making progress.

Arnett, a program coordinator for the Bats and Wind Energy Cooperative (BWEC), a partnership between conservationists, government agencies and the wind industry, is experimenting with a bat deterring device. The latest model in development contains 16 speakers that emit ultrasound, which should jam bat echolocation and coerce a bat to change its flight course. They are now working to test the device and evaluate reduction in bat kills.

Arnett’s second solution is to increase the minimum wind speed necessary for wind turbine blades to start turning. Research shows that bats are more likely to be hit on calm nights in late summer and fall. Because this could cause a drop in a wind facility’s energy production, Arnett had trouble getting a company to sign on to study this solution. It was the world’s leading provider of wind power, Iberdrola Renewables, that finally agreed to collaborate, giving Arnett access to all 23 turbines on its Casselman Wind Power Project in Pennsylvania. According to Andy Linehan, the company’s wind permitting director, the benefits of finding a solution to the bat fatality problem outweighed the costs of producing slightly less energy. “We market ourselves as a green industry,” he says. “If we’re going to continue to take that seriously, we’ve got to continue to show it.“

The experiment was a success. By curtailing production during low wind conditions, and increasing the wind speed threshold required to jump-start the turbines, bat fatalities dropped between 56 and 92 percent. The costs to the company were small: a less than one percent overall power loss for the year. Arnett now wants to test this strategy at several more sites.

“This is a worldwide issue,” says Barclay, who is also a science advisor for BWEC. “Most of the research is being done in North America, but wind turbines are going up at an incredible rate in other parts of the world, and so the research we do here can have a potentially bigger impact.”


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Comments (10)

i love birds

Posted by on May 1,2009 | 09:54 AM

Could these bats be returning to sites where formerly roosting trees stood? I am also concerned about change of use and resulting habitat fragmentation and degregation for all wildlife species, winged or not. Expedited removal of insect eaters and natural plant propagators from the biological ecosystem will upset the natural balance. In addition former prisine landscapes once disturbed will invite invasive species either necessitating increased use of pesticides for control or change to native flora and fauna affecting food sources, stopover and contiguous breeding sites for all wildlife species. Putting wind turbines into formerly pristine forested landscapes or farm fields and then planting crops whose food sources attract resident and migratory winged species is a recipie for disaster. Common sense tells you that increasing the number of wind turbines will result in more wildlife deaths, even if adequate research is done in a scientific manner because this is not an exact science and can be influenced by weather and habitat change and that monitoring needs to be done on a continuous basis. Some research has also suggested that migratory birds are also more likely to experience turbine collisions on low wind nights. As noted, more wildlife and people friendly options would be to subsidize solar and wind on each residential building but then, people could actually become self-sufficient.

Posted by Vicci on April 6,2009 | 10:05 PM

Is anyone else struck by the irony of the wind turbine industry "solution" to the bird/bat kill problem - which is to turn the turbines OFF? These turbines are a nightmare; they wreak havoc on the environment, kill bats and birds, negatively impact human health - and produce energy in only tiny portions of their rated capacity - literally only when the wind blows. They are little more than a financial grab for tax breaks. A much better return with less environmental impact would be to subsudize - or outright give out - solar panels to households throughout the country. The power would be made right at the source of consumption and not require $100 billion in new power grid, and wouldn't kill birds and bats or drive people literally crazy from lack of sleep.

Posted by luca dring on March 26,2009 | 01:30 PM

These wind turbines are NOT benign. It isn't only bats that have problems with turbines! Massive (450' tall -- that's 45 stories) turbines generate low-frequency sound that is now recognized to cause a host of human health problems, starting with chronic sleep deprivation - that can lead to more serious physical and psychological problems, to increased heart attack risk, and light flicker from the massive blades triggering epileptic seizures in prone individuals. Medical studies are documenting sleep deprivation from low frequency turbine sound in people living as far as 2-3 miles from wind turbine projects. This month the Northern Maine Med Center issued a statement urging a moratorium on all new turbine projects until health issues are further studied. Excellent resources are windturbinesyndrome.com windaction.org and vawind.org

Posted by gobo spring on March 25,2009 | 06:59 PM

Very informative. I wonder whether the deterrent devices can be installed at some point *after* the turbines are erected? There are so many turbines currently going up, yet we are on the cusp of a solution to so many bat kills

Posted by Kevin Walsh on March 20,2009 | 12:58 PM

Thank you for this article. It does however leave me wondering as to what happened with the Altamont Pass. Is it still in operation, killing thousands of birds? I hope that there will be updates in the future, informing your readers as to what was/will be done.

Posted by roman kozak on March 11,2009 | 01:12 PM

I was pleased to see a comprehensive report into this problem. I have often considered the potential threat to birdlife from ever expanding windfarms. One potential measure to protect birds or bats would be the use of noise frequency which could be generated to the rotation of the turbines themselves.

Posted by Maxwell (North Norfolk, England ) on March 7,2009 | 03:59 AM

Ah! Another glitch in a seemingly perfect solution! It seems that wherever human technology and wildlife meet, damage is inevitable. Whatever is done to remedy the situation will add trouble and expense, but it is probably worth it in the long run. Offhand, the possibility of a mesh guard or a sonic deterrent occurs to me.

Posted by Christine G. on March 6,2009 | 04:07 PM

I am a firm proponent of wind and solar power generation, but I agree that we need to take steps to protect wildlife. The thought of a Golden Eagle being needlessly killed is a sad thing indeed. I hope they can develop some mesh or netting that will protect the little critters - be they eagles or bats.

Posted by Phillip T. Alden on March 6,2009 | 01:28 PM

I didn't know that bats had problems with wind turbines, thank you for writing about this issue. I've never seen a bat, except for on the television. I see that Australia gets a mention, that's where I live. It's good that writers and scientists are taking a global perspective. An easy to read and well-written article. Keep up the good work!

Posted by Elizabeth9 on March 5,2009 | 09:50 PM



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