Published on August 29th, 2008 | by Timothy B. Hurst18
Study Finds Wind Turbines Killing Bats Without Even Hitting Them
August 29th, 2008 by Timothy B. Hurst
Researchers at the University of Calgary found that the vast majority of bats found dead at a wind farm in Southwest Alberta suffered severe injuries to their respiratory systems consistent with a sudden drop in air pressure – called barotrauma.1 The findings, published in the most recent issue of the journal Current Biology could potentially have far-reaching consequences on bat populations.
Barotrauma is a condition resulting from drastic changes in air pressure occurring, for example, when the bats fly through an area where the pressure drops dramatically, such as it does near a spinning turbine blade.
Historically, less than one bat fatality per turbine per year is considered normal, according to scientists. At this particular wind farm, the numbers were closer to 18 bats per turbine. But researchers found that the vast majority of dead bats had no visible trauma, as if they were being struck by a blade tip moving at 250 km/hr.
Upon further examination they discovered that all of the bats had suffered from severe hemmoraging of blood and died as from their lungs filling with fluid. The study shows that 90% of the bats examined after death showed signs of internal hemorrhaging consistent with barotrauma.
While it’s important to note that little is known about their population sizes, therefore, what proportion of migratory bats are being afffected by the syndrome, researchers said their deaths could have serious impacts on bat populations.
“Slow reproductive rates can limit a population’s ability to recover from crashes and thereby increase the risk of endangerment or extinction,” said biologist, Prof. Robert Barclay, of the University of Calgary.
All three species of migratory bats killed by wind turbines fly at night, eating thousands of insects—including many crop pests—per day as they go. Therefore, bat losses in Southwest Alberta could have very real effects on ecosystems as far away as Mexico and places in between.
According to co-author, PhD candidate Erin Baerwald, “Given that bats are more susceptible to barotrauma than birds, and that bat fatalities at wind turbines far outnumber bird fatalities at most sites, wildlife fatalities at wind turbines are now a bat issue, not a bird issue.”
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1. Baerwald, Erin F., Genevieve H. D’Amours, Brandon J. Klug and Robert M.R. Barclay. “Barotrauma is a significant cause of bat fatalities at wind turbines.” 2008. Current Biology Volume 18, Issue 16, R695-R696.
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