DESCRIPTION: A large raptor, the bald eagle has a wingspread of about 7 feet. Adults have a dark brown body and wings, white head and tail, and a yellow beak. Juveniles are mostly brown with white mottling on the body, tail, and undersides of wings. Adult plumage usually is obtained by the 6th year. In flight, the bald eagle often soars or glides with the wings held at a right angle to the body.
STATUS: On August 8, 2007, the bald eagle was removed from the List of Endangered and Threatened Wildlife (Federal Register 72: 37346-37372). The bald eagle is still protected under the Bald and Golden Eagle Protection Act and the Migratory Bird Treaty Act. On July 12, 1995, the U.S. Fish and Wildlife Service reclassified the bald eagle from endangered to threatened throughout the 48 conterminous States (Federal Register 60:35999-36110). Previously, the eagle was protected under the Bald Eagle Protection Act of 1940 and the Endangered Species Act in 1978 (Federal Register 43:6230-6233). Delisting was proposed in 1999 because recovery goals were reached around 1990 and the bald eagle was been determined to be recovered by the bald eagle recovery team (Federal Register 64: 36453-36464).
REASONS FOR CURRENT STATUS: The major factors leading to the decline of the bald eagle were persecution by humans and lowered reproductive success following the introduction of the pesticide DDT in 1947. DDT residues caused eggshell thinning which led to broken eggs. Bald eagle populations began to show signs of recovery 10 to 20 years after DDT use was banned. Population increases have been assisted by protective buffer zones around nests, reduced shooting, and restoration of aquatic habitat. Currently, shoreline development may be the most limiting factor impacting populations.
REPRODUCTION AND DEVELOPMENT: The breeding season of bald eagles varies with latitude. The general tendency is for winter breeding in the South with a progressive shift toward spring breeding in northern locations. In the Southeast, nesting activities generally begin in early September; egg laying begins as early as late October and peaks in late December.
The female does most of the nest construction but the male assists. The typical nest is constructed of large sticks with softer materials such as dead weeds, cornstalks, grasses, and sod added as nest lining. Bald eagle nests are very large, sometimes measuring up to 6 feet in width and weighing hundreds of pounds. Many nests are used year after year. Eagles may lay from one to three eggs, but the usual clutch size is two eggs. A second clutch may be laid if the first is lost. Incubation lasts 34 to 38 days. The young fledge 9 to 14 weeks after hatching but parental care may continue for another 4 to 6 weeks. Bald eagles reach sexual maturity at 4 to 6 years of age. Life span is not known, but it is potentially long since eagles have been known to live for 50 years in captivity.
RANGE: The bald eagle is found throughout North America from northern Alaska and Canada, south to southern California and Florida. Each year, about 300 bald eagles winter in South Dakota along the Missouri River or in the Black Hills. After a long absence, bald eagles were found nesting in South Dakota around 1993.
POPULATION LEVEL: In 1997, the number of breeding pairs in the lower 49 was > 5,000 pairs. The total population was estimated at around 100,000 individuals in 1999 including Alaska and British Columbia.
HABITAT: Bald eagles are associated with riparian habitat along coasts, rivers, and lakes. Winter roost sites typically consist of clusters of large cottonwoods associated with food sources such as waterfowl and fish. Eagles tend to use the same roosts each year. Roost sites usually are in areas protected from harsh weather and human disturbance.
Nests are found in mature, old-growth trees located in close proximity to water with adequate food resources. Quality of habitat appears more important than distance to water. Suitable habitat supports a diversity of prey and experiences little human disturbance. As with winter roost sites, nest trees usually are used for many years.
MANAGEMENT AND PROTECTION: Although bald eagle populations have increased, they continue to be threatened by habitat loss, environmental contaminants (i.e., organophospate pesticides, heavy metals, and oil spills), electrocution by powerlines, and human disturbance. Management strategies include use of buffer zones around nests, and continued monitoring of populations.
Bald eagles nest in South Dakota from January to August with new nest sites appearing each year. A buffer zone of one-quarter mile is recommended during the nesting season.
Bald eagles are protected by Federal and State laws enforced by U.S. Fish and Wildlife Service and State Game Departments.
Information summarized from:
Buehlar, D. A. 2000. Bald Eagle (Haliaeetus leucocephalus). In The Birds of North America, No. 506 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Fisher, L. E., J. G. Hartman, J. A. Howell, and D. E. Busch. 1981. A survey of wintering bald eagles and their habitat in the Lower Missouri Region, Denver, Colorado.
Steenhof, K. 1976. The ecology of wintering bald eagles in southeastern South Dakota. M.S. Thesis. University of Missouri, Columbia, Missouri. 148 pp.
US Fish and Wildlife Service. 1983 Northern States Bald Eagle Recovery Plan (6.51 MB). USFWS, Denver, Colorado. 120 pp.
Last updated: May 3, 2011