University of Minnesota researchers are evaluating eagles' auditory responses as part of an ongoing effort to prevent fatalities caused by wind turbine collisions.
Funded by the U.S. Department of Energy, the researchers tested a variety of sounds to determine what eagles can hear, with the ultimate goal of using their findings to add sounds to wind turbines to prevent casualties.
Raptors that hunt during the day are among the most common species of bird killed by wind turbines, according to the U.S. Fish and Wildlife Service. Minnesota has the largest bald eagle population in the continental United States, said Julia Ponder, executive director of the University’s Raptor Center.
Investigators from the Raptor Center, St. Anthony Falls Laboratory and Center for Applied and Translational Sensory Science (CATSS) collaborated to map the sounds bald eagles, golden eagles and red-tailed hawks can hear.
“[Eagles] are federally protected animals in this country, they have a special status and are obviously very powerful birds. They’re important in food webs, but also important as symbols to different communities in the United States — native communities as well as non-native,” said Jeff Marr, associate director of engineering and facilities at the St. Anthony Falls Laboratory.
Using birds from the University’s Raptor Center, the investigators used technology from CATSS to send a variety of sounds with different levels and frequencies to the raptors while they were under anesthesia. Through their research, they were able to pinpoint the range of sounds these eagles and red-tailed hawks responded to the most.
Going forward, Ponder said the hope is to use these findings to do further studies on eagle behavior and see how the sounds deter eagles from flying into wind turbines. After that, she said she hopes their research will help develop technology that adds sound to wind turbines nationally.
The United States has more than 60,000 wind turbines as of October, according to the U.S. Geological Survey.
“There’s always the challenges of alternative energy, which we’re all for because it’s a huge issue for our country and the world,” Ponder said. “We need to make sure we’re doing it in an intelligent way and not having too much impact.”
Right now, agencies like the U.S. Fish and Wildlife Service work with a variety of industries, including wind companies, in order to make sure they are mindful of wildlife. Biologist Mags Rheude, who specializes in eagles at the Minnesota Fish and Wildlife Service branch, said although eagle-turbine collisions do not happen as often as with other birds, it is important to take preemptive measures to protect these raptors.
“The reason we’re concerned about eagles is because they are a very long-lived bird. If an eagle dies, it takes quite a while to replace that eagle in the population,” Rheude said. “We like to work with developers to minimize their impact, because really things that we do to help eagles will also help a lot of other wildlife.”