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Researchers share new information on golden eagles

MONTEREY – Due to increasing industrial wind energy projects, biologists are finding it more important than ever to learn more about the migration habits and habitats of golden eagles on the East Coast.

The Virginia Society of Ornithology held its annual board retreat in Monterey last weekend, and following dinner at The Highland Inn, the group heard from husband and wife researchers Trish Miller and Michael Lanzone of Pennsylvania.

Miller is a wildlife biologist with the Division of Forestry and Natural Resources at West Virginia University. She is also a doctoral candidate in the ecology program at Pennsylvania State University working under Dr. Todd Katzner, WVU research assistant professor.

She and Lanzone have both worked at the Carnegie Museum of Natural History in the Powdermill Avian Research Center.

Along with biologists at the Virginia Department of Game and Inland Fisheries, these researchers are providing important information about golden eagles, especially about what might negatively affect their presence in the East.

“We started this project in 2005,” Miller told the group last Saturday. Katzner had been interested in starting a research project in Pennsylvania, she explained. “We felt there was a need due to the explosion of wind power development.”

What started as research from three people has now grown, and includes researchers from several agencies in multiple states and Canada.

Worldwide, there are 125,000 to 250,000 golden eagles in six subspecies, Miller said. In North America, there are two populations – roughly 35,000 golden eagles in the West, but fewer than 2,000 in the East. One of the threats to the eagles’ population is the pesticide DDT. Though it’s no longer used, the chemical has a long half-life and is still accumulating. High levels are found in the eagles’ eggs. Consequently, reintroduced populations haven’t nested successfully in the East, Miller said. They are further threatened by mountain top removal, wind tower construction, and gas extraction – all of which creates habitat loss.

Because the eagles use thermal updrafts of the ridge/valley regions, “increasing wind power development is a real concern,” she said. “These turbines can be up to 550 feet with blades 150 feet long, and they sweep a two-acre area.” Golden eagles and other birds did not evolve with the instincts to deal with such structures. “They’re not used to having these beg egg beaters in the sky, so they don’t look for them,” she said.

In one location they studied, Hawk Mountain, they found that 88 percent of the golden eagles flew within the swept area of the blades. “So, there’s potential for conflict,” she said.

Miller and her colleagues advocate close study for siting wind turbines to avoid migratory routes. “We know turbines can be sited safely,” she said.

The biologists study the birds’ patterns by banding them with special tracking equipment developed by Lanzone. Miller explained a site is chosen and baited, usually with deer carcasses, and researchers wait for an eagle to arrive. When they do, a net is shot from a canon to capture them. “Once we have them in hand, we put a hood on and then booties.” That allows the birds to calm down enough the researchers can outfit them with bands and a transmitting device like a small backpack. They also take physical measurements, and get blood samples to collect data on the birds’ DNA and toxicology.

Once released, the birds’ telemetry equipment allows researchers to track their movements by satellite. What they find, Miller said, is that golden eagles migrate and winter over in the central Appalachian region, right where many wind projects are proposed or already built. Thus, Miller and her colleagues have concluded these raptors are the species most at risk from industrial wind power development.

This is true for the Highland New Wind Development site in Highland County, too, Miller said. Eagles have been mapped flying through the site on Allegheny Mountain where Virginia’s first wind project is proposed but has not been constructed. “There are seven different birds using (the site), Miller noted.

Thanks to Lanzone’s transmitting technology and the data they have gathered, “we can now identify the ridges with the greatest potential for conflict,” she said.

“We know these turbines can be moved to safer places, and that’s our overarching goal.”

Following the presentation, VSO president Dr. Andrew Dolby announced the group would donate $500 to the research project.