Wildlife Diversity Notebook:
The American Bald Eagle
Scientific Name: Haliaeetus leucocephalus
Status: In 1995 The United States Fish and Wildlife Service officially downlisted the bald eagle from “Endangered” to “Threatened” in the lower 48 states including West Virginia.
West Virginia Status: The first documented bald eagle nest in West Virginia was discovered in 1981. Eleven nests produced 21 eaglets in 2001. These nest sites were located in Grant, Hardy, Hampshire, Pendleton , and Mineral counties. In 1999, a pair nested in Hancock County but were apparently unsuccessful in producing young. In 2001, a pair nested on Blennerhassett Island in the Ohio River near Parkersburg , but no young were hatched. Twelve nests were active in 2002, but not the nest on Blennerhassett Island. Non-breeding eagles have been seen in most areas of the state.
Description: The image of the adult bald eagle is familiar to most Americans. Adult eagles have distinctive white heads making them appear bald; the tail feathers are likewise white. The body and wings of the adult bird are dark brown. The beak, eyes, and legs are yellow or golden, while the talons are black. Adult birds can reach a length of 30 inches with a wingspan approaching 7 feet. Female eagles weigh 10 to 14 pounds and are usually larger than males which usually weigh 8 to 9 pounds.
Juvenile bald eagles lack the white heads and tails characteristic of adults, and can be confused with golden eagles. Their plumage is brown or mottled brown and white throughout. They can be distinguished from the comparably sized golden eagle by their bare lower legs. These are heavily feathered on golden eagles. Immature birds have darker beaks and eyes than adults. Their plumage gradually becomes lighter until the birds reach their fourth or fifth year when they take on the appearance of adults. Young eagles have long wing and tail feathers making them appear larger than the heavier adults.
Range: The bald eagle's breeding range has traditionally covered all of North America south of the arctic circle. Currently the northern subspecies breeds in Alaska and Canada while its southern counterpart inhabits most of the lower 48 states. The largest concentrations of southern bald eagles are centered around Florida, Maine, the Chesapeake Bay region, the Great Lakes region, and the Pacific Northwest.
Habitat: Bald eagles usually nest in large trees near large streams or lakes. Their migration routes follow river systems or mountain ranges which run in a general north-south direction. Bald eagles often winter along large interior or coastal bodies of water that remain free of ice. Except during migration, bald eagles are seldom found far from water.
Diet: Bald eagles feed primarily on fish, although small mammals, birds, and carrion can make up a substantial part of their diet. Eagles are opportunistic feeders, often relying on crows, ravens, and vultures to lead them to carcasses or injured prey.
Life History: When they are four or five years old, eagles choose a mate. The pair will often stay together for several years, perhaps for life. Nest preparation commences in the early spring, usually before a complete thaw has occurred (as early as February). Nests are built of sticks and twigs with an interior lining of moss or grass. Broods usually consist of two to three eggs, and both the male and female eagle incubate the eggs for a period of 21 to 46 days. The nestlings are quite helpless, relying on both parents for food and protection for most of the 10 to 13 weeks that they are in the nest.
Eagles begin their southward migration as the ice begins to appear in the fall. They choose locations with open water and ample food for their winter home. Often conditions are difficult in the winter as many birds converge on an area with a limited food supply. At the first sign of moderating weather, the birds begin their northern migration, often returning to the nest they used the previous year. They repair and improve the nest by adding sticks and vegetation. Because they are always being refurbished, eagle nests can become very large.
Threats and Prospects: The bald eagle was first protected under the “Bald Eagle Act,” a largely symbolic piece of legislation, which was passed in 1940. The Act strove to reduce persecution by ranchers who feared losses of young lambs and calves to these large raptors (birds of prey). The loss of wetlands to farming and development was also a problem for the eagle which relied on such habitats for food. By the mid 1900s, eagle numbers were perilously low throughout most of the lower 48 states.
The use of the pesticide DDT was perhaps the most severe culprit in the decline of the eagle. Before it was banned in the early 1970s, DDT entered the food chain and caused a dramatic decline in the reproduction of eagles and other birds of prey. DDT was found to cause female birds to lay eggs with thin shells which were crushed by the weight of the adults trying to incubate them. Since DDT was banned in the United States, bald eagle populations in this country have generally been on the upswing.
Population increases, coupled with the implementation of measures to protect eagle nest sites under the Endangered Species Act, have led to the downlisting of the species from “Endangered” to “Threatened” throughout much of its range.
Problems still persist however for the bald eagle. Habitat loss still threatens eagles in many areas, and pollution of our rivers and lakes can impact eagles which feed on contaminated fish. The inadvertent shooting of misidentified eagles as well as poaching continues to plague eagle populations. The future of the bald eagle in the continental United States will depend on the extent to which current problems can be reduced. West Virginia can now boast of more eagle nests than at any time in the past, and there is no reason to expect that this trend won't continue if we continue to protect this great bird and the habitats on which it depends.
Additional Comments: The bald eagle was designated our national symbol in 1782 over the objection of Benjamin Franklin who thought the bird was of “bad moral character.” Franklin preferred the wild turkey.
Produced by the WVDNR Wildlife Diversity Program.