The Bald Eagle
The National Emblem of the United States, the Bald Eagle was threatened with extinction in the lower 48 states because of DDT poisoning. Protection under the Endangered Species Act, together with reintroduction programs, brought the populations up. They were reclassified as Threatened in 1994 and were taken off of the Threatened list in June 2007.
A Bald Eagle is a very large raptor with adults’ unmistakable brown body with white head and tail. They have a large yellow hooked bill, long broad wings held flat while soaring, yellow eyes and yellow feet. They average 28-38 inches tall, wingspan about 80 inches and weigh between 7-12 pounds. Female and male are alike in plumage, female larger. The Immature Bald Eagle has variable patterned with dark brown and white. It takes five (5) years to acquire full adult plumage and sexual maturity. Beak is blackish gray. Eyes are a dark brown.
Their breeding is season is from late December – end of March. They engage in aerial courtship, which sometimes consists of the pair locking talons in midair and descending several hundred feet in a series of somersaults. When the female is ready to copulate, she makes a head down, bowing gesture, and the male closes his talons and mounts her. Bald Eagles mate for life. A mated pair adds on to their nest each breeding year; which is primarily built of sticks.
Females lay a clutch of 1-3 eggs (The eggs are 2.9 inches long and 2.2 inches wide on average) with incubation period of between 33-38 days. Eggs are laid 1-4 days apart and full incubation begins after all eggs are laid. Nest duties among the pair are shared equally; both the male and female will hunt and offer food to the eaglets. Bald Eagles are primarily fish eaters.
When hunting, the Bald Eagle either seeks its prey from a perch or from high in the sky, then swoops down and snatches up the prey in its talons or it will steal its prey from other birds like Ospreys. Bald Eagles are only partially migratory; if they have an access to open water, they might remain at that nesting site year around. Eagles choose their migratory routes to take advantage of thermals, updrafts and food source.
There are three methods of flight used during migration. Eagles ascend in a thermal and then glide down, circle steadily down a stream of thermals, or use rising air generated by the wind as it sweeps down against a cliff or other raised features of the terrain.
Eagles once numbered around 50,000 in the contiguous Unites States, but by the time the U.S. had restricted the use of DDT in 1972, only about 400 breeding pairs remained. Under the Endangered Species Act of 1973, the eagles have made a steady recovery with breeding pairs now over 10,000. A tremendous effort has been made to protect and restore the Bald Eagle populations. Some states now support effective nest monitoring and programs to release young birds into the wild. Plus there is a banding program where the young eaglets are banded in the nest before they take flight.
COOL FACTS • Humans are the most important source of mortality for this threatened species. • Bald Eagles occasionally hunt cooperatively, with one individual flushing prey towards another. • The immature Bald Eagle has a prolonged period of exploration lasting four years. Some young from Florida have wandered north to Michigan, and birds from California have reached Alaska. • Much to Benjamin Franklin’s dismay, the Bald Eagle was adopted as the national emblem in 1782. He said that the Bald Eagle was a bird of bad moral character (stealing food) and recommended the turkey instead.
