Is the region’s explosion of windmills a threat to migrating birds, including golden eagles?
A fledgling partnership between the National Aviary and the Johnstown-based Allegheny Plateau Chapter of the Audubon Society is working to answer that question.
The groups are trapping golden eagles as they migrate past the Allegheny Front Hawkwatch near Central City. Global positioning transmitters are attached to the birds’ backs to track their movements.
The study is designed to provide information that may help to save one of the most majestic birds of eastern North America from the perceived threat posed by the rapid development of wind farms along a critical migration route.
“Most people don’t even know there are golden eagles in Pennsylvania because there are so few of them,” said Todd Katzner of the National Aviary, who is overseeing the project. “There is a dearth of information on these birds so, from a very basic level, we’re trying to figure out how many there are, where they fly, where they spend the winter ““ simple things like that.
“But there is a broader context ““ in this case, the development of wind power along much of the mid-Appalachian region. This area is a really important corridor for migrating raptors, and our goal is to try to develop, essentially, maps that will allow us to identify places where we think development of wind power will be safe for eagles and areas where development of wind power will potentially be a danger for eagles.”
Katzner said the groups are not attempting to thwart the wind-energy trend, but merely better understand the industry’s impact on eagles and other species.
“We believe there is a role for wind power, and there is a way to develop wind power in an eagle-friendly way,” he said. “To do that, though, you need to have background information.”
Katzner and others are catching eagles that pass by the hawkwatch ““ a mountaintop lookout in Somerset County where volunteers keep a vigil each spring and fall, counting the number of various species of birds that migrate through the area. The birds ““ and several species of migrating insects ““ are drawn by air currents above the ridge line that provide lift, allowing the migrants to expend less energy as they follow the mountains southward.
Although many species of birds pass the hawkwatch each fall, Johnstown veterinarian Tom Dick said the golden eagle is probably the most impressive.
“The golden eagle always attracts attention, because its the real bird,” he said. “It’s tough as nails. It will take down young deer, eat foxes and wolves. It’s not the bald eagle-type that sneaks food away from others.”
Little is known about the eastern golden eagle subspecies, including where it nests and where it winters. Scientists don’t even know how many there are, although it is suspected that the birds are not numerous.
Because much of the eastern golden eagle population is believed to pass over the Allegheny Front Hawkwatch each fall, it is the logical center for research.
“There’s a lot of unanswered questions,” Dick said. “We take blood because we want to find out about genetic diversity. We also want to know about the population size. If they have a lot of diversity, it means that they’re OK and there’s a pretty healthy population. We suspect that there are about 1,000 in the eastern United States, max, and that they’re almost all here.”
To follow the birds’ progress south, the volunteers harness small transmitters to the birds that enable them to determine not only where they fly, but how high. The transmitters will last for about three years and cost $10,000 a bird, which makes it an expensive project.
Just two eagles were equipped with transmitters during the past fall’s migration, and they already are yielding data that the public can view on the National Aviary Web site, www.aviary.org. But, Katzner said, about a dozen will be needed before the information is of scientific use.
“Two birds are nice and we get pretty pictures,” Katzner said. “But we need a sample size of 10 or 12 birds. We are looking for other funding for the project. In a year or two, hopefully, we will have data sufficient for scientific peer-review publication, which is really the only way to produce a useful report.”
By Joe Gorden
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