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The bald eagle is the largest bird of prey found in Alaska. It is named for its conspicuous white head and tail. The distinctive white adult plumage is not attained until five or more years of age. Immature birds lack this easily identifiable characteristic and can be confused with the golden eagle. The immature bald eagle’s unfeathered lower leg, and whitish wing linings on the forward part of the wings, can be helpful distinctions where the two species coexist.
Bald eagles are only partially migratory. If they possess access to open water, they will remain at that nesting site year-round, while those that do not have access to water leave that area in the winter and migrate south or to the coast.
Fish is the main diet of the bald eagle including herring, flounder, pollock and salmon. Bald eagles may also prey on waterfowl, small mammals, sea urchins, clams, crabs and carrion.
Like other birds of prey, bald eagles regurgitate a small pellet containing undigested bones and hair after they eat.
Bald eagles often use the same nest each year. Nest trees are usually close to water, provide a clear view of the surrounding area, and provide sparse cover above the nest. Nest building begins in April, and both the male and female gather nest material. In late April, two or three eggs are laid several days apart. Incubation lasts around 35 days. When the young hatch, sibling rivalry is common and the weaker, usually younger chick, does not survive. Surviving young leave the nest after approximately 75 days. They attain adult plumage and breed at four to five years of age.
Found only in North America, bald eagles are more abundant in Alaska than anywhere else in the United States.
Reproductive success can be affected by pesticides in the eagles’ prey. Bald eagles in Alaska seem to be reproductively healthy, but contaminants have been recorded in Alaskan fish populations and in bald eagles. A greater threat to Alaska’s bald eagle population is destruction of their nesting habitat and nest disturbances.
With statehood in 1959, the bald eagle in Alaska received federal protection under the Bald and Golden Eagle Protection Act of 1940. This act made it illegal to kill or possess an eagle, alive or dead, or to posses any part of an eagle, including the feathers.
Bald eagles were endangered or eliminated throughout most of the Lower 48 states as a result of habitat destruction, illegal shooting, pesticides and poisoning. Populations are recovering in many states.
The Cornell Lab of Ornithology
University of Michigan Museum of Zoology Animal Diversity Web
Alaska Department of Fish and Game