March 2001

Bald eagles have increased in Washington State from about 105 nesting pairs in 1980, to about 650 pairs today. The present spring population of up to 2,000 eagles compares to perhaps 6,000- 10,000 eagles when Lewis and Clark first visited Washington in 1805.

Many additional eagles that breed in Alaska and British Columbia come to Washington for the winter to feed on spawned salmon. The last state-wide winter survey in 1989 counted almost 2,900 eagles, and there may now be up to 3-4,000 present during winter.

The recovery of bald eagles in recent years can be attributed to several factors, including the ban on the use of the pesticide DDT, protection of nesting and roosting habitat, the use of non-toxic shot for waterfowl hunting, and probably, a reduction in shooting and persecution.

In Washington, a small portion of eagle nests are in parks and other protected public lands, but 2/3 of nests are located on private lands. Private landowners who have cooperated in protecting nesting birds and their habitat deserve our thanks in helping eagles recover to their present numbers.

As a result of recent increases in bald eagles, they may be removed from the federal list of threatened and endangered species in 2001and Washington Department of Fish and Wildlife is reviewing their status as a state threatened species. However, bald eagles will still be protected by state and federal laws.

Bald Eagle Biology

Bald eagles have a wing span of 6 ½ to 7 ½ feet, and weigh 6-15 pounds. Juvenile and subadult eagles lack the white head and tail, and display various patterns of dark brown, light brown, gray, and white. Eagles do not acquire their distinctive adult plumage until about 5 years of age. Bald eagles typically do not breed until 6-8 years of age. Once they have established a territory they often return to it year after year.

Bald eagles in Washington are migratory, and eagles that nest in Washington typically move north after nesting and spend several weeks each year feeding on early salmon runs in coastal British Columbia and southeast Alaska. Many of the eagles that concentrate along rivers in Washington during winter are birds that nest in Alaska, British Columbia, and Montana. Washington nesters usually return to their territories by late January.

Bald eagles are not fussy eaters ,and will take advantage of a wide variety of foods, including fish, birds, carrion, and miscellaneous small mammals, mollusks, and crustaceans. Fish, including spawned salmon, carp, suckers, bullheads, and summers die-offs of perch are among the wide variety of fish eaten. Birds that are frequent prey include gulls, waterfowl, coots, seabirds, pigeons, and crows.

Habitat needs of bald eagles include timber with large trees near water. In Washington, 97% of nests are within 3,000 ft of a marine, lake or river shore. Large trees along shorelines are important perch sites for foraging. At night, eagles often perch together in communal roosts. Roost sites are selected that provide a favorable microclimate, such as protection from prevailing winds. Many roosts located near winter food sources are used year after year.

The longevity record for bald eagles in the wild is at least 28 years, but the average life span is often much shorter. One study estimated the maximum lifespan for birds from the Yellowstone area at 15.4 years and a study of Alaska birds estimated the average at 19 years. Sources of adult mortality include fighting with other eagles, and a variety of human-related causes including shooting, electrocution on powerlines, vehicle collisions, and poisoning.

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