By Jeff Gillies, firstname.lastname@example.org
Great Lakes Echo
July 9, 2009
Wind turbines cut air pollution, but they may mean respiratory trouble for bats flying nearby.
“Basically, their lungs explode,” said Barb Barton, biologist with the Michigan Natural Features Inventory.
Though wind turbines can kill bats by smacking them out of the sky, the huge spinning blades more often take out bats without touching them.
Turbine blades spinning at up to 200 mph leave in their wake a vortex of low pressure, Barton said. Bats get caught in the vortex, and the change in pressure ruptures capillaries in the bats’ lungs.
Bats have large, pliable lungs compared with birds, whose compact, rigid lungs better withstand pressure changes.
Birds get much of the attention when people think of conflicts between wind turbines and wildlife. Altamont Pass Wind Farm in California famously knocks off dozens of endangered golden eagles every year.
But at some wind turbine sites 20 times more bats are dying than birds, said Maarten Vonhof, assistant professor of biology and environmental studies at Western Michigan University. That can add up to thousands of dead bats per year on a single wind farm.
That sounds like a lot of bats that won’t be feasting on pest insects like moths and mosquitoes. But scientists still aren’t sure if wind turbines are killing enough bats to threaten the health of the whole population, Vonhof said.
Bats fly at night and hide out during the day. They’re tough to capture and count, he said. Researchers can estimate the size of bird populations and track migration patterns by capturing and banding individual animals, but that method doesn’t work well with bats.
“As a consequence, there’s not many studies that have estimated population size for bats,” Vonhof said.
And a count of dead bats under a wind turbine doesn’t mean much if you don’t know how many bats there were in the first place.
Using a $100,000 federal grant, Vonhof and his team will estimate the impact of wind power on eastern red bat populations using a genetic measuring stick.
“If you boil it down, it refers to the proportion of the population that’s actually passing on its genes to the next generation,” he said.
They’ll use DNA markers from wild-caught and turbine-killed bats to guess how many eastern red bats are reproducing every year. Eastern red bats are one of three migratory bat species in the Great Lakes region and have been one of the most common species found dead near turbines.
The the number of bats Vonhof comes up with will be smaller than the total population, but it could give researches something to work with when estimating impacts of wind turbines.
Tracking Bats along Lake Michigan
Though Vonhof’s study could clear up the mystery around bat population sizes, he said little is known about the patterns of bat migration around the Great Lakes.
“The thought is that migratory bats will go down the edges of the lakes much as migratory birds do, but I don’t think we really know that at all,” he said.
That’s where Barton comes in. She’ll use another $100,000 federal grant to monitor bat and bird migration along the Lake Michigan coast next summer.
“We’re thinking that they may visually use the coastline for their north-south migration,” Barton said.
Barton will haul microphones and radar equipment to four or five sites in northwest lower Michigan, a region deemed ripe for wind energy development in a recent report by Michigan’s Wind Energy Resource Zone Board.
The specialized microphones record bat and bird calls up to 600 yards away. The recordings will show which species are flying, and the radar will track the size of the animals and the speed and direction of their flight.
Barton said they’ll look for migrating bats and birds right on the shore and three miles inland.
“If they’re right on the shoreline, then we know that putting wind turbines right on the coastline is not a good idea and we can recommend siting them a certain distance away to minimize impacts to bats,” she said.
Barton said she’d like to assess bat and bird migration along each Great Lake’s coast, but future funding could depend on how well things go on Lake Michigan.
“I think it might depend on our success, which I anticipate will be really high.”
Vonhof said wind power is part of a two-pronged set of threats to bats right now. The other prong is a fatal disease hitting hibernating bats in caves.
“The hibernators are getting strongly affected by white nose syndrome,” he said. “The migrating bats are getting strongly effected by wind power development.”
The money for these two grants will come from the Department of Energy, which is sending $2.6 million to the Great Lakes region for wind energy research and development. Half a million dollars will go to researching impacts of wind development on wildlife.