For the Birds Radio Program: Bald Eagle migration 1987
Eagles are back!
(Recording of a Bald Eagle)
Bald Eagles are back in the northland. I saw one circling over the Lakeside neighborhood in Duluth last week, and there have been many other sightings around town. Eagles and crows are the true harbingers of spring up here, so it must be time to shake off the old cabin fever blues and get outside.
An adult Bald Eagle is easy to recognize with its white head and tail, enormous yellow bill and blackish body. It takes its name from the mistaken impression that its head is bald–in reality, it’s fully feathered. Purists can take comfort in the fact that in Middle English, bald spelled b-a-l-l-e-d meant shining white. It takes young birds as much as four or five years to develop the white head and tail– meanwhile, they’re a blotchy, nondescript brown. They’re as big as the adults, though, so they aren’t too hard to recognize. In flight, eagles beat their wings in long, labored strokes until they rise on a thermal air current or hitch a ride on an airstream–then they can glide effortlessly for minutes, their wondrously long wings outstretched, the primary feathers jutting out like fingers.
There are two species of eagles in North America–the Bald and the Golden Eagle. Goldens are rare in the eastern U.S., including Minnesota and Wisconsin, although a few migrate over Hawk Ridge each fall, and there are occasional sightings at the national wildlife refuges in both states. The Golden Eagle is often accused of carrying off babies and eating sheep. There are actually no documented cases of any bird carrying off a baby–after all, big as it is, a Golden Eagle weighs at most only about 14 pounds. One scientist measured the weight-carrying capacity of an 11-pound golden eagle in 1937 and discovered that it couldn’t take off at all with a 5 1/2 pound weight.
Golden Eagles do eat a lot of rodents, snakes, and carrion. They’re birds of the open country, and so are specially adapted to surviving winter in the harsh mountains and plains–their legs are fully feathered down to the toes presumably as protection against their cold environment. Bald Eagles, on the other hand, have no feathering on their legs. Bald Eagles fish for most of their food, and feathered legs would drag too much in the water.
This time of year, Bald Eagles usually pick up a lot of winter- killed fish, although there probably won’t be many of those this year. They also eat road-killed animals, and are sometimes seen with ravens and crows at roadsides. I’ve seen a couple of them hunting over fields in winter–probably catching mice, but fish is their preferred food. They grab the fish in their powerful feet, called talons, but Bald Eagles are pretty lazy, and would just as soon pick up dead fish or steal them from ospreys or other eagles as catch their own.
The expression “Eagle Eyes” is a good one–the eye balls of a 12- pound Bald Eagle are about the same size as those of a 200-pound man, and have far greater visual acuity and sensitivity to movement. But the expression “Legal Eagle” is not appropriate–as far as anyone can tell, eagles have no particular expertise in matters of jurisprudence.
(Recording of a Bald Eagle)
This is Laura Erickson, and this program has been “For the birds.”