October 6, 2008
Golden Eagles Making Their Way to Pennsylvania
By Bob Frye
Pennsylvania routinely attracts a lot of non-resident hunters, but some of the most spectacular ones to show up this fall will be a breed apart.
Over the next few weeks, golden eagles -- magnificent birds whose wings can span 87 inches -- will begin migrating through Pennsylvania. They'll start to show up in noticeable numbers in mid- to late October, with the peak of the migration coming in November.
If you don't know a lot about the bird you're looking at, you won't be alone.
"The average member of the public doesn't even know they migrate through here," said Dan Brauning, the ornithologist who heads the Pennsylvania Game Commission's wildlife diversity section.
Truth be told, even bird experts don't know a lot about golden eagles -- or at least the ones that exist on the East Coast.
Golden eagles are present in greatest concentrations in the western United States and Canada, and for years were thought to be a species that needed large expanses of open ground, Brauning said.
A distinct population of eastern goldens is thriving, however. Most -- maybe as many as 1,500 a year -- simply pass through the state on their way from Quebec, Newfoundland and Labrador to Tennessee, Alabama and Georgia, following mountain ridges, said Todd Katzner, director of the department of conservation and field research at the National Aviary in Pittsburgh.
But some are even overwintering in Pennsylvania, he said.
"And we would never really have guessed that because you never see them. They're one of our most cryptic species," he said.
In the West, golden eagles feed on the small mammals that inhabit open country, like rabbits, prairie dogs and the like. That habitat doesn't exist here, so how the eagles survive a winter is a bit of a mystery, Brauning said.
"It seems from some of our telemetry that these birds are concentrating in large forest areas in winter. And we don't know what they're eating," Brauning said. "There aren't a lot of bunnies there."
It could be that they feed on things like gut piles left behind by hunters and carcasses that result from deer-vehicle collisions, Katzner said. Some ongoing research is looking at that, but not a lot is known for sure yet.
What is certain is that golden eagles -- like many raptors once persecuted as vermin -- are enjoying a comeback, said Keith L. Bildstein, director of conservation science for Hawk Mountain Sanctuary in Kempton.
"Their population has been increasing of late, and so long as there is adequate habitat, there's no reason that should not continue," he said. "We hope so, anyway. They're great birds."
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