Harper the golden eagle has returned to Bernheim Forest for a fifth year, completing a 1,600 mile migration from his summer range in the Canadian wilderness.
Harper is one of two eagles Bernheim researchers have tagged with solar transmitters to learn more about the migration routes and habits of these splendid raptors.
The data provide valuable insight. For example, on the return flight, Harper flew at speeds up to 74 miles per hour, reaching heights more than twice that of the Empire State Building.
But often, the data raise just as many questions as they do answers.
Earlier this year, researchers tagged a second eagle, Athena. They watched as the duo hunted and roosted together in the forest around Bernheim. But when it came time to migrate, the pair split.
Athena flew northeast, up through Michigan. Harper headed northwest through Illinois. Both skirted the banks of Lake Superior, but on opposite ends. Still, their destination was the same. They both summered in the wilderness near Churchill, Manitoba.
Interestingly, there was only a 20 mile-difference in each of their routes.
How do these eagles navigate to the same place 1,600 miles away? How do they know where they’re going?
“That’s the big question. There’s still a lot of mysteries around these birds,” said Andrew Berry, Bernheim conservation director. “Particularly the ones that use the eastern United States as their winter range… not a lot is known about them.”
What’s clear from the data, is that the eagles avoid densely populated areas, preferring stopovers in agricultural and small protected areas for hunting and resting. At both ends of their migration, the eagles rely on large forested areas for habitat.
“These large forested blocks, which they seem dependent on, like Bernheim, are really in short supply,” Berry said.
Wilderness areas like Bernheim are vital, not just for apex predators like golden eagles, but for a number of migratory species including songbirds, bats and monarch butterflies, he said.
For migratory species, it’s not enough to just protect one piece of land. These creatures are part of complex, interdependent ecosystems. Migration patterns for Kentucky’s part-time inhabitants span from the northern reaches of Canada to southern Brazil.
“Without all of those components, you know, these species are incredibly fragile and that’s why we’re seeing a lot of species in decline right now,” Berry said.
As for Athena, she was located earlier this week headed due south across Indiana. She spent a day roosted along the Yellow River, then flew to a stopover near Eddy Creek of the Tippecanoe River.
On Nov. 24th, researchers pinpointed her west of Salem, Indiana, headed in the direction of Bernheim.
It remains to be seen whether Harper and Athena are a breeding pair. Only time — and the solar transmitters they carry — will tell.