More than 600,000 bats may have been killed at wind farms in the continental US last year. That’s trouble for agriculture: the US Geological Survey estimated in 2011 that the bats’ natural pest-control saves the industry at least $3 billion a year.
At wind farms, bats are most often killed when they are struck by spinning turbine blades. They may also sometimes die from a sudden change in air pressure, which harms their respiratory systems.
A recent study set to appear in the journal BioScience has found that more than half a million bats – possibly up to 900,000 – died at wind farms in 2012.
Mark Hayes, who authored the study, said those numbers could add up in years to come and substantially reduce the bat population. He said that preventing bat deaths at wind farms should be easy.
Researchers are testing two main techniques: changing the speed that turbines begin spinning and sending out acoustic signals that would cause bats avoid wind farms.
Cris Hein, who coordinates the wind energy program for Bat Conservation International, said fatality rates are lower in the Pacific Northwest, because most wind farms are not located near trees, where bats roost as they migrate.
“Our concern right now is that as wind development creeps into the Cascades or the coastal range, more forested areas, we may see fatality rates similar to the east,” Hein said. Study author Hayes said the Appalachian Mountains have the highest estimates of bat deaths.
Hein said the eastern red bat, the hoary bat and the silver haired bat are most affected by wind turbines. The latter two species fly through Washington and Oregon and make up almost 97 percent of fatalities.
One challenge is that researchers don’t know the number of bats of individual species in the US. Hayes said bats most often killed at wind farms are migratory tree bats, which usually travel across regions in large numbers in the fall.
“This is a phenomenon that we know when it’s going to happen, and we know where it’s going to happen. It’s going to happen at night, and it’s going to happen in close proximity to wind energy turbines,” Hayes said. “If we can combine that information with a little bit of fine tuning and knowledge of where the bats are going to be at a particular time of year, I think we can design some reasonably effective solutions.”
The American Wind Energy Association, an industry advocacy group, said it follows sitting guidelines from the US Fish and Wildlife Service to help minimize bat deaths. The group joined with researchers and conservationists in 2003 to form the Bats and Wind Energy Cooperative, which researches bat activity before and after wind turbine construction.
Hayes said bat mortality at wind facilities is one of the biggest problems facing bat conservationists right now – the other being white nose syndrome, a fungus that has wiped out entire hibernating bat colonies in the eastern half of the country.
Copyright 2013 EarthFix.