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    Bald Eagle Life History

    Habitat

    Habitat ForestsBald Eagles typically nest in forested areas adjacent to large bodies of water, staying away from heavily developed areas when possible. Bald Eagles are tolerant of human activity when feeding, and may congregate around fish processing plants, dumps, and below dams where fish concentrate. For perching, Bald Eagles prefer tall, mature coniferous or deciduous trees that afford a wide view of the surroundings. In winter, Bald Eagles can also be seen in dry, open uplands if there is access to open water for fishing. Back to top

    Food

    Food FishFish of many kinds constitute the centerpiece of the Bald Eagle diet (common examples include salmon, herring, shad, and catfish), but these birds eat a wide variety of foods depending on what’s available. They eat birds, reptiles, amphibians, invertebrates such as crabs, and mammals including rabbits and muskrats. They take their prey live, fresh, or as carrion. Bald Eagles sometimes gorge, ingesting a large amount of food and digesting it over several days. They can also survive fasting for many days, even weeks.Back to top

    Nesting

    Nest Placement

    Nest TreeBald Eagles nest in trees except in regions where only cliff faces or ground sites are available. They tend to use tall, sturdy conifers that protrude above the forest canopy, providing easy flight access and good visibility. In southern parts of their range, Bald Eagles may nest in deciduous trees, mangroves, and cactus. It’s unknown whether the male or the female takes the lead in selecting a nest site. Nests are typically built near the trunk, high up in the tree but below the crown (unlike Osprey nests).

    Nest Description

    Bald Eagles build some of the largest of all bird nests—typically 5 to 6 feet in diameter and 2 to 4 feet tall, and ranging in shape from cylindrical to conical to flat, depending on the supporting tree. Both sexes bring materials to the nest, but the female does most of the placement. They weave together sticks and fill in the cracks with softer material such as grass, moss, or cornstalks. The inside of the nest is lined first with lichen or other fine woody material, then with downy feathers and sometimes sprigs of greenery. Ground nests are built of whatever’s available, such as kelp and driftwood near coastal shorelines. Nests can take up to three months to build, and may be reused (and added to) year after year.

    Nesting Facts
    Clutch Size:1-3 eggs
    Number of Broods:1 brood
    Egg Length:2.3-3.3 in (5.8-8.4 cm)
    Egg Width:1.9-2.5 in (4.7-6.3 cm)
    Incubation Period:34-36 days
    Nestling Period:56-98 days
    Egg Description:Dull white, usually without markings.
    Condition at Hatching:Covered with light-gray down; eyes brown; gape, legs, and skin pink.
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    Behavior

    Behavior Soaring (raptor)Bald Eagles are powerful fliers—soaring, gliding, and flapping over long distances. In one of several spectacular courtship displays, a male and female fly high into the sky, lock talons, and cartwheel downward together, breaking off at the last instant to avoid crashing to earth. Bald Eagles frequently harass birds including Ospreys and other eagles to steal their food, and occasionally do the same to mammals such as river or sea otters. On the ground, Bald Eagles walk in an awkward, rocking gait. Capable of floating, a Bald Eagle may use its wings to “row” over water too deep for wading. Though often solitary, Bald Eagles congregate by the scores or even the hundreds at communal roosts and feeding sites, particularly in winter. These groups can be boisterous, with birds jostling for position and bickering over prey. During breeding season you may see Bald Eagles defending their territories from a variety of intruders, including raptors and ravens, coyotes and foxes. When feeding at carcasses, Bald Eagles may push Black and Turkey Vultures out of the way; other species including ravens, coyotes, bobcats, and dogs sometimes hold their own. Bald Eagles are often harassed or chased by their fellow raptors and by songbirds including blackbirds, crows, and flycatchers. Back to top

    Conservation

    Conservation Low ConcernThe Bald Eagle’s recovery is a spectacular conservation success story, and numbers have increased between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 250,000, with 88 percent spending some part of the year in the U.S., 31 percent in Canada, and 8 percent in Mexico. The species rates a 9 out of 20 on the Continental Concern Score and are not on the 2016 State of North America's Birds' Watch List, but are a U.S.-Canada Stewardship Species. Once abundant in North America, the species became rare in the mid-to-late 1900s—the victim of trapping, shooting, and poisoning as well as pesticide-caused reproductive failures. In 1978 the bird was listed for protection under the Endangered Species Act. Since 1980, gentler treatment by humans along with the banning of DDT (the bird’s main pesticide threat) have led to a dramatic resurgence. By the late 1990s, breeding populations of Bald Eagles could be found throughout most of North America. In June 2007, the bird’s recovery prompted its removal from the Endangered Species list. Continuing threats to Bald Eagle populations include lead poisoning from ammunition in hunter-shot prey, collisions with motor vehicles and stationary structures, and development-related destruction of shoreline nesting, perching, roosting and foraging habitats. They are still vulnerable to environmental pollution, as evidenced by the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska. An estimated 247 Bald Eagles died from oil exposure. Population levels in the Sound decreased by almost four percent the following year. The local population returned to pre-spill levels by 1995.Back to top

    Credits

    Buehler, David A. 2000. Bald Eagle (Haliaeetus leucocephalus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

    Dunne, Pete. 2006. Pete Dunne's essential field guide companion: Houghton Mifflin Harcourt.

    Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

    Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

    Sauer, J. R., D. K. Niven, J. E. Hines, Jr. Ziolkowski, D. J., K. L. Pardieck, J. E. Fallon and W. A. Link. The North American breeding bird survey, results and analysis 1966-2015 (Version 2.07.2017). USGS Patuxent Wildlife Research Center 2017.

    Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

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