Hoary Bat photo: Jerry Oldenettel
Based on past TreeHugger posts at least, the jury is still out on whether wind turbines really kill so many birds that we ought to overly worry about it. Well, a recent study published in Current Biology focuses not on the number of birds killed by industrial-scale wind turbines but on why more bats are actually killed than birds. The article doesn’t go into the numbers of bats which are killed but does provide evidence as to the cause of those that do. Science Daily provides the details:
Drops in Air Pressure, Not Blade Contact the Killer
Researchers from the University of Calgary say that 90% of the dead bats they examined showed signs of internal hemorrhaging such as could happen with a sudden drop in air pressure—a condition known as barotrauma. About 50% of the bats showed signs of physical contact with the turbine blades.Report co-author 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.
Bats are more at risk for barotrauma than birds due to the structure of their lungs: Bird lungs are more rigid than bat lungs and can withstand more easily a sudden drop in air pressure.
So Why Should We Care About Bat Deaths?
The majority of bats killed by wind turbines are migratory bats—hoary bats, eastern red bats, silver-haired bats—which eat thousands of insects per night (including crop pests) as the move from one region to another. Bat losses in one region could have negative effects on ecosystems far away from the site of wind turbines. Also, because bats have long lives and reproduce slowly, their ability to recover from population crashes is limited.