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Bald Eagle Fact Sheet

Description: The bald eagle (Haliaeetus leucocephalus) belongs to the family Accipitridae.  This very large diurnal raptor of the sea eagle group has a wingspread of 6-7 feet. It occurs principally near water and feeds preponderantly on fishes. Its weight ranges from 6 1/2 to 14 pounds and is from 28 to 38 inches in length. The sexes are similar in appearance with the female always larger. (There is some overlap between small females and large males). Typical adult plumage is usually acquired from the spring of the 5th calendar year of life to fall. Head, neck, tail and all coverts are white. Other feathering is blackish brown. The beak and cere are yellow to orange-yellow. The iris is pale to buffy yellow. Legs and feet are deep yellow. The talons are black. The plumage of juvenile birds varies. The first plumage is usually very dark brown or blackish. In the spring of the second year the head is frequently a light buffy brown and the upper back frequently exhibits a whitish or buffy inverted triangle on otherwise dark feathers. Underparts are generally dark. In the third year there is an increased lightening of the head and darkening of the dorsal area. Generally, the underparts remain dark but some individuals have a mottled white belly. In the fourth year, the head is white with brown flecking on the forehead and crown and usually a brownish line or stripe through and back from the eye. Body feathering is usually dark as in later plumages.

Field Identification: At times they soar and glide with flat wings (no dihedral) in thermals and updrafts. Flapping flight is used primarily for short distances, for carrying food or for going to and from a roost. Singles, pairs, and small numbers are usual, but assemblies of scores, hundreds or thousands occur especially in late fall and winter at places where food is readily available (salmon run or abundant hares and rabbits). The bald eagle has a larger beak and unfeathered legs in comparison to the golden.

Habitat: Bald eagles usually inhabit coastal areas, estuaries, and unfrozen inland waters. Generally speaking, a high amount of water to land edge where prey is concentrated or generally available is preferred. An unimpeded view is also important. Both horizontal and vertical aspects are used--a preference for margins of forest stands (horizontal) and trees projecting above the forest canopy (vertical). Where trees are low or absent, any location commanding a wide view is preferred.

Trees selected for nesting are typically old growth and taller than their surroundings. Ideally, the nest lies below the top of the crown in a live tree where the young are sheltered above from the elements and the parent birds have adequate aerial access.

Distribution: The only sea eagle on the North American mainland. Breeds and is a year around resident on the Aleutian chain and along south coastal Alaska south to northern California. (Historically nested along the entire Pacific Coast from Alaska to Baja California). It is also resident year around as a breeding bird surrounding the Great Lakes and along the eastern seaboard south to the Chesapeake Bay region. Isolated populations also exist year around in Florida and along the Gulf coast to Texas, and in parts of Arizona and southern Colorado. It is found seasonally as a breeder or a migrant in most of North America except the Arctic and subarctic regions.

Reproduction: Bald eagles normally breed for the first time at age five, however records exist for first time breeding at age four in areas where the population is in recovery and no competition for nest sites exists. The nest territory is usually located adjacent to or along the shore of a lake, river, or seashore. Islands are often preferred. Nests are usually built in a coniferous tree that is tall relative to surrounding trees. The nest is built within the crown and an easy approach from the direction of the nearest water is essential. In treeless areas bald eagles will nest on a high place such as a hillock or cliff ledge. Two eggs are usually laid, and three more often than one. Siblicide is well known among bald eagles with the smaller eaglet disappearing between the third and eighth week. Survival of both young at a nest appears to depend on the ability of the parents to provide food.

Habits: The still- or perch-hunting technique has a high success rate for bald eagles. The hunting bird watches from a tree or cliff and swoops down to seize its prey, braking as it nears the surface. Though not as successful, they also hunt by flying or by circling high overhead. Bald eagles have been seen flying close to the surface of the sea and then dropping between the troughs to take seabirds by surprise. In the same fashion, they have been seen following the contours of the Aleutian tundra and hunting ptarmigan in the manner of a gyrfalcon. There are several accounts of bald eagles flushing flocks of coots ahead of them that fly together striking the surface of the water with their wings. Eventually one or more of the coots will break away and the eagle captures it. Eagles have also been seen hunting solitary coots by hovering above a diving coot and grabbing it as it emerges for air.

Where fish abound, eagles land on shore and wade into the water, at times up to their breasts, and they may submerge their heads to capture fish. In season, dead and dying salmon are a staple food, and the ease with which they are caught must be especially beneficial to the welfare of inexperienced young eagles. Eagles have been seen wading into the Chilkat River in Alaska until almost afloat, and then seizing a dead or dying salmon with one foot and then tugging the prey ashore with the other.

Taken from: Handbook of North American Birds, Volume 4. Edited by Ralph S. Palmer. Yale University Press, 1988.