The Bald Eagle (Haliaeetus leucocephalus), the official emblem of the United States, belongs to a group of birds known as fish eagles, which includes one or more species in most of the world except for the American tropics. Bald Eagles are generally found close to water and often occur in rather dense concentrations in certain areas during the winter. They breed from Alaska and northern Canada south to Baja California, Sonora, Arizona, New Mexico, Texas, and the Gulf coast from southeastern Texas to the Florida Keys (breeding is very local in interior North America). Southern and coastal adults often do not migrate, but birds from the far northern interior migrate south in winter. Although they often feed on carrion, including dead fish washed up on shorelines, and may steal food captured by other birds such as Ospreys (Pandion haliaetus), Bald Eagles are also capable of capturing their own prey in shallow water or on land. Their diet is usually dominated by fish when it is available, but also includes birds, mammals, and a variety of other small animals. Bald Eagles generally do not breed until four or five years of age and may mate for life. The large stick nests (which are constructed by both sexes) may be re-used and enlarged year after year. The 2 eggs (range 1 to 3) are incubated by both parents for 34 to 36 days. First flight of young birds is typically at around 10 to 12 weeks. (Kaufman 1996; AOU 1998)

During the late 19th century and first two thirds of the 20th century, Bald Eagle populations seriously declined over most of their range. Although the species had received some earlier legal protection, in 1978 the Bald Eagle was listed under the U.S. Endangered Species Act as Endangered in most of the lower 48 states (and as Threatened in the remainder). During the subsequent quarter century, however, the number of Bald Eagles in the lower 48 increased 25-fold to around 10,000 nesting pairs. This recovery is generally attributed to the 1973 banning in the United States of the insecticide DDT (which impairs normal egg development in birds of prey), protection from shooting, improved water quality, habitat protection, and hacking programs to actively reintroduce Bald Eagles to areas from which they had disappeared. The sustained and substantial population increases led to the downlisting of the Bald Eagle's status in the lower 48 states from Endangered to Threatened in 1995 and then to its de-listing altogether in 2007.

The bald eagle is native to North America and originally bred from central Alaska and northern Canada south to Baja California, central Arizona, and the Gulf of Mexico. It now has been extirpated in many southern areas of this range.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDING: central Alaska, northern Yukon, northwestern and southern Mackenzie, northern Saskatchewan, northern Manitoba, central Ontario, central Quebec, Labrador, and Newfoundland, south locally to the Commander and Aleutian Islands, southern Alaska, Baja California (both coasts), Sonora (Brown et al. 1988), New Mexico, Arizona, Texas Gulf Coast, and Florida (including the Keys); very local in Great Basin and prairie and plains regions in interior North America, where breeding range recently has expanded to include Nebraska and Kansas. NON-BREEDING: generally throughout the breeding range except in the far north (AOU 1983, Sibley and Monroe 1990), most commonly from southern Alaska and southern Canada southward. The Chilkat Bald Eagle Preserve, Alaska, supports the largest wintering population anywhere (Ehrlich et al. 1992). Winter concentrations occur in British Columbia-northwestern Washington, along the Missouri and Mississippi rivers, and in northern Arkansas. One of the largest fall (mid-October to mid-December) migrant concentrations (200-300 birds at any one time, close to a thousand individuals through the season) occurs at Hauser Lake near Helena, Montana.

The plumage of an adult bald eagle is brown with a white head and tail. Immature eagles are irregularly mottled with white until the fourth year. Their legs are feathered half way down the tarsus, and the beak, feet, and eyes are bright yellow. Bald eagles have massive tarsi, short and powerful grasping toes, and long talons. The talon of the hind toe highly developed in both species, and it is used to pierce vital areas while the prey is held immobile by the front toes. The wing span of an eagle can reach seven and a half feet .

Average mass: 3175 g.

Length: 94 cm

Weight: 5244 grams

Adults differ from other eagles in having both a white head and white tail (head of white-tailed eagle may look white at a distance). Bald eagle has a proportionately larger head and bill than does the golden eagle, in the immatures of which the white is confined to the base of the primaries and the base of the tail. Bald eagle lacks the long wedge-shaped tail of Steller's sea-eagle. Bald eagle's neck is shorter and tail is longer than in white-tailed eagle.

• Terrestrial
• Freshwater
• Marine

Bald eagles are able to live anywhere on the North American continent where there are adequate nest trees, roosts ands feeding grounds. Open water such as a lake or an ocean, however, is a necessity.

Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; mountains

Comments: Breeding habitat most commonly includes areas close to (within 4km) coastal areas, bays, rivers, lakes, or other bodies of water that reflect the general availability of primary food sources including fish, waterfowl, and seabirds (Andrew and Mosher 1982, Green 1985, Campbell et al. 1990). Preferentially roosts in conifers or other sheltered sites in winter in some areas; typically selects the larger, more accessible trees (Buehler et al. 1991, 1992). Perching in deciduous and coniferous trees is equally common in other areas (e.g., Bowerman et al. 1993). Communal roost sites used by two or more eagles are common, and some may be used by 100 or more eagles during periods of high use. Winter roost sites vary in their proximity to food resources (up to 33 km) and may be determined to some extent by a preference for a warmer microclimate at these sites. Available data indicate that energy conservation may or may not be an important factor in roost-site selection (Buehler et al. 1991). In Saskatchewan lakes, density was positively correlated with abundance of large fishes (Dzus and Gerrard 1993). In winter, may associate with waterfowl concentrations or congregate in areas with abundant dead fish (Griffin et al. 1982); often roosts communally at night in trees that are used in successive years. Wintering areas are commonly associated with open water though in some areas eagles use habitats with little or no open water if other food resources (e.g. rabbit or deer carrion) are readily available. Avoids areas with nearby human activity (boat traffic, pedestrians) and development (buildings) (Buehler et al. 1991). BREEDING: Usually nests in tall trees or on cliffs near water. Nest trees include pines, spruce, firs, cottonwoods, oaks, populars, and beech. Ground nesting has been reported on the Aleutian Islands in Alaska, in Canada's Northwest Territories, and in Ohio, Michigan, and Texas. Nests located on cliffs and rock pinnacles have been reported historically in California, Kansas, Nevada, New Mexico and Utah, but currently are known to occur only in Alaska and Arizona. Same nest may be used year after year, or may alternate between two nest sites in successive years. In British Columbia, nests with overhead canopy of foliage were most successful (Palmer 1988). See Livingston et al. (1990) for model of nesting habitat in Maine, Wood et al. (1989) for characteristics of nesting habitat in Florida (most nests in live pine trees). In Oregon, most nests were within 1.6 km of water, usually in largest tree in stand (Anthony and Isaacs 1989). In Colorado and Wyoming, forest stands containing nest trees varied from old-growth ponderosa pine to narrow strips of riparian vegetation surrounded by rangeland (Kralovec et al. 1992).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Most eagles that breed in Canada and the northern U.S. move south for winter. Migrates widely over most of North America (AOU 1983); moves generally E-SE across Canada and the Great Lakes region to the northeast coast of the U.S. In the northern Chesapeake Bay region, radio-tagged northern migrants arrived in late fall (mean date 21 December) and departed in early spring (mean date 27 March); radio-tagged southern migrants arrived throughout April-August and departed June-October (Buehler et al. 1991). See Palmer (1988) for fairly detailed review of seasonal movements in various regions.

Defended territories are relatively small; fourteen in Alaska varied from 11-45 hectares and averaged 23 ha (Hensel and Troyer 1964), and territory radius around active nests averaged 0.6 km in Minnesota (Mahaffy and Frenzel 1987). Feeding home ranges surrounding active nests are undoubtedly much larger, depending on proximity to food sources and abundance of food. Minimum home range of breeding birds in Saskatchewan was 7 square kilometers (Gerrard et al. 1992); on the Columbia River, Oregon, breeding home ranges averaged 21.6 square kilometers (Garrett et al. 1993).

Winter home ranges can be very large, especially for nonbreeding birds. An immature wintered in Arizona over an area of >40,000 square kilometers and spent the summer in the Northwest Territories over a summer range of >55,000 square kilometers (Grubb et al. 1994). Maximum distance between feeding area and night roost site was less than 16 km in winter in Missouri (Griffin et al. 1982). In north-central Arizona, February-April home range of immatures averaged 400 square kilometers; birds moved frequently and roosted singly or in small groups (Grubb et al. 1989).

Bald eagles are primarily fish-eaters that prefer salmon, but will also take avian prey. Waterfowl are an important secondary food source, and eagles also eat small mammals such as rabbits, seabirds, and carrion. When hunting, the Bald Eagle either seeks its prey from a perch or from high in the sky, then swoops down and snatches up the prey in its talons. Another method used by bald eagles to gain food is theft; Bald Eagles are often seen stealing prey from other birds.

Comments: Feeds opportunistically on fishes, injured waterfowl and seabirds, various mammals, and carrion (Terres 1980). See Haywood and Ohmart (1986), Kralovec et al. (1992), Brown (1993), and Grubb (1995) for diet of inland breeding populations in Arizona, Colorado, and Wyoming. Hunts live prey, scavenges, and pirates food from other birds (e.g., osprey) and, in Alaska, sea otter (Watt et al. 1995, Condor 97:588-590). See Palmer (1988) for further information on hunting methods. In the Columbia River estuary, tidal flats and water less than 4 m deep were important foraging habitats (Watson et al. 1991). See Caton et al. (1992) for information on foraging perches used in Montana. Sheep carcasses were significant food sources in winter in Oregon (Marr et al. 1995, Wilson Bulletin 107:251-257).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: BREEDING AREA occurrences probably number over 150 in British Columbia and Alaska. The total number of occupied territories (not equivalent to breeding area occurrences) in British Columbia and Alaska is probably at least 7000 (Gerrard 1983); there are about 1000 on Vancouver Island alone (British Columbia CDC 1993). Kjos (1992) estimated there were 3,014 occupied bald eagle territories in the lower 48 states.

10,000 - 100,000 individuals

Comments: Gerrard (1983) estimated that Alaska and British Columbia have approximately 48,000 bald eagles. Blood and Anweiler (1991) gave North American estimates of 70,000, with 21,000 in British Columbia. Alaska population is about 30,000, and perhaps almost that many occur in western Canada. Estimated number of breeding pairs in Canada in the early 1990s was 15,000-20,000 (Kirk et al. 1995). The reported number of nesting territories in the lower 48 states in 1990 was 3,014 (Kjos 1990). Population estimates (number of occupied territories) based on the 1990 breeding season survey were as follows: northern states, 1165; Chesapeake Bay, 235; Pacific states, 861; southeastern states, 722; southwestern states, 27; total, 3010 (USFWS 1990). In 1992, there were 149 nesting pairs in New England.
NON-BREEDING: The winter count for 1992-1993 was about 400 in Maine, 70 in Massachusetts, 61 in Connecticut, 23 in New Hampshire, 12 in Vermont, and a few in Rhode Island (End. Sp. Tech. Bull. 18(2):20). Winter count in late 1980s yielded about 11,250 bald eagles in the lower 48 states.
See Busch (1988) for information on status in the southwestern U.S. See Brown et al. (1988) for status in Sonora, Mexico.

Commonly roosts communally, especially in winter. See Curnutt (1992) for information on the dynamics of a year-round communal roost in southern Florida.

In Montana, the introduction of shrimp (Mysis relicta) had a cascading effect through the food chain, ultimately causing displacement of bald eagles (Spencer et al. 1991).

Comments: In the Columbia River estuary, foraging activity was most common at low tide and first daylight (Watson et al. 1991). In Arizona, foraging activity during the breeding season peaked at 0800-1000 and 1600-1900 MST (Grubb 1995).

Average lifespan

Status: wild: 369 months.

When the female is ready to copulate, she makes a head down, bowing gesture, and the male closes his talons and mounts her. The males's tail goes down and hers goes up. The process is completed when their cloacae meet. Bald Eagles sometimes even copulate out of season. This behavior may account for the strong loyalty between mates. There is not any sound evidence, however, that supports the idea that eagles mate for life.

A mated pair adds on to their nest each breeding year. The nests are primarily built of sticks and can eventually weigh up to two tons. Bald Eagle nests are among some of the largest nests in the world. Females lay a clutch of one to three eggs, but usually two. Incubation lasts from five to six weeks. One problem that greatly hampers the recovery of the species is sibling competition. A female lays her eggs a few days apart, and incubation begins with the first egg. One to two days is the normal age difference between eaglets. Older hatchlings are able to dominate the youngers ones for food because of their size. In a three-egg brood, the third chick has little chance of survival. Nest duties among the pair are shared equally; both the male and the female will hunt and offer food to the eaglets.

Average time to hatching: 35 days.

Average eggs per season: 2.

Average age at sexual or reproductive maturity (male)

Sex: male: 1460 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 1460 days.

Clutch size is 1-3 (usually 2). Incubation lasts about 5 weeks, by both sexes. Second hatched young often dies. Young first fly at 10-12.5 weeks, cared for by adults and may remain around nest for several weeks after fledging. Generally first breeds at about 5-6 years. Adults may not lay every year.

Over the years, the Bald Eagle population has suffered from excessive hunting and pollution. In the early part of the century, hunting eagles was a popular sport. Eagles were shot not only for their feathers, but also because they posed a "threat" to livestock (e.g. sheep) and hampered the fishing industry. In recent years, however, pollution has greatly contributed to the demise of the species. As a result of both land and water pollution, a significant amount of the Bald Eagle food supply has been killed. In particular, the use of pesticides such as DDT had been the greatest threat to the species. Pesticides are often found in fish, the major food supply for eagles. DDT in a female's body disturb the shell-making process, causing her to produce very weak shells or no shells at all. Eagles once numbered around 50,000 in the contiguous United States, but by the time the U.S had restricted the use of DDT in1972, only about 800 bredding pairs remained. Under the Endangered Species Act of 1973, however, the eagles have made a steady recovery. Breeding pairs now number close to 3000, and there has been an increase in the number of hatchlings per nest. Only in Canada and Alaska, however, are eagles found in abundance.

A tremendous effort had been made to protect and restore the bald eagle population. Some states now support effective nest-monitoring and programs to release young birds into the wild. Federal protection has involved monitoring populations, improving protection, setting up captive breeding programs, relocating wild birds, and establishing a wide-ranging public information program.

Bald eagles are currently listed as threatened by the U.S. Fish and Wildlife Service and by the Michigan Department of Natural Resources. They are protected by the U.S. Migratory Bird Act.

US Migratory Bird Act: protected

US Federal List: threatened

CITES: appendix ii

State of Michigan List: threatened

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread distribution in North America; large numbers of occurrences, many of high quality, particularly in Alaska and British Columbia, but suffered great decline in southern and eastern part of range earlier this century; still susceptible to a number of threats, particularly environmental contaminants and excessive disturbance by humans; recent rangewide improvement in numbers and the protection offered by governments prevent it from being ranked any higher.

Global Short Term Trend: Relatively stable to increase of 25%

Comments: As of early 1990s, populations in many areas had rebounded from the low levels that occurred before DDT use was banned in the U.S. The population increase in recent years has been accomplished through protection and active management, as well as through enhanced reproduction after the DDT ban. Populations have been increasing in the contiguous 48 states: the number of nesting territories nearly tripled between 1980 and 1990 (Kjos 1992). In the lower 48 states, breeding population has doubled every 6-7 years since the late 1970s (USFWS, Federal Register, 12 July 1994, p. 35585). In Alaska and British Columbia numbers have been generally stable at about 48,000 (Gerrard 1983, Campbell et al. 1990). Populations are stable and "healthy" in Alaska and western Canada. As of the early 1980s, most Canadian populations were reasonably stable, and problem populations in southwestern Ontario and the maritime provinces were showing signs of recovery (Brownell and Oldham, 1984 COSEWIC report). Overall, populations have increased in Canada in recent decades (Kirk et al. 1995, Hunter and Baird 1995). A significant increase was recorded in migration counts in northeastern North America, 1972-1987 (Titus and Fuller 1990). The breeding population in the Chesapeake Bay region increased 12.6% per year from 1986 to 1990; the mean minimum survival rate of all eagles was 91%; however, eagle habitat there is being converted to human development at a rapid rate (Buehler et al. 1991). In California in the late 1980s, the winter population was stable, and the breeding population was increasing in numbers and range (California DF&G 1990). Increasing in Arizona in the 1980s (Forbis 1988).

Global Long Term Trend: Increase of 10-25% to decline of 50%

Degree of Threat: BC

Comments: Major threats include habitat loss, disturbance by humans, biocide contamination, decreasing food supply, and illegal shooting (Evans 1982, Green 1985, Herkert 1992). In 1992, many died in northern Utah after eating poisoned bait set out by ranchers. Breeding success still is being affected by environmental contaminants in the diet along Lake Superior in Wisconsin (Kozie and Anderson 1991). Greatest potential threats in Florida include urban development and commercial timber harvest (Wood et al. 1989). The Chilkat Bald Eagle Preserve, Alaska, which supports the largest wintering population anywhere, was threatened by a proposed copper mine in the early 1990s (Ehrlich et al. 1992). See Witmer and O'Neil (1990) for information on estimating cumulative impacts of multiple hydroelectric development and logging activities in Washington. See Montopoli and Anderson (1991) for a model used to evaluate the cumulative effects of selected forms of human disturbance in the Greater Yellowstone ecosystem. As of the mid-1990s, the population in the southwestern U.S. continued to face threats and required intensive management to maintain current population levels (1994 End. Sp. Tech. Bull. 19(5):18).

Generally susceptible to human intrusion, but "show a high degree of adaptability and tolerance if the human activity is not directed toward them" (Beebe 1974). However, chronic disturbance results in disuse of areas by eagles (Fraser 1985).

Management Requirements: Recovery has been assisted by intensive management that included systematic monitoring, enhanced protection, captive breeding, relocation of wild birds, and publicity (Matthews and Moseley 1990).

Knight and Knight (1984) recommended a 450 m buffer between a human in a canoe and a feeding eagle. For northern Chesapeake Bay, Buehler et al. (1991) recommended a 1360-m-wide shoreline management zone that extends 1400 m inland to encompass nonbreeding roost sites and provide a buffer from human disturbance. Another study recommended a 250-m buffer between a human on land and an eagle in a shoreline tree. A 500-m buffer around the nest may be adequate (see Fraser et al. 1985). In Michigan, 75% of all alert and flight responses to human activity occurred when activity was within 500 m and 200 m, respectively; vehicles and pedestrians elicited the highest response frequencies. Anthony and Isaacs (1989) made recommendations for Oregon: size of areas for nest-site management should be 50-250 ha, with size and shape depending on surrounding vegetation, topography, and eagle behavior; human activities within 800 m of nests should be restricted from 1 January to 31 August; clearcut logging, road building, hiking trails, and boat launch facilities should not be allowed within 400 m of nests. In Arizona, pedestrians were the most disturbing human activity; eagles were more often flushed from perches than from nests and were most easily disturbed when foraging; eagle response to disturbance frequencies were 64% at distances less than 216 m, 45% at 216-583 m, and 24% at distances greater than 583 m (Grubb and King 1991). Along northern Chesapeake Bay, flush distances because of approaching boats averaged 204 m in winter, 176 m in summer (Buehler et al. 1991, which see for further information on the effects of human activity).

In the Columbia River estuary, management of eagle foraging habitats should emphasize protection and enhancement of tidal flats (Watson et al. 1991).

See Busch (1988) for a discussion of management activities in the southwestern U.S., Lefranc and Glinski (1988) for management recommendations.

Supplemental feeding can be used in efforts to replace diminished supplies of natural foods, provide food free of environmental contaminants, provide essential nutrients, enhance survival of subadults, manipulate distribution of populations, increase nesting success, support released captive-bred birds, and/or afford opportunities for public viewing and education; potential disadvantages of supplemental feeding include prohibitive costs, the loss of natural and cautious behavior, dependence on these food supplies which may alter migration patterns, and increased potential for disease transmission (Knight and Anderson 1990).

See Grubb (1980) for information on construction and use of an artificial nest structure.

Global Protection: Many to very many (13 to >40) occurrences appropriately protected and managed

Comments: Protected in the United States by the Bald Eagle Protection Act, the Migratory Bird Treaty Act, and the Endangered Species Act. Listed as Endangered or Threatened in the lower 48 States, but proposed to be downlisted to Threatened in all 48 states except portions of the American southwest, and proposed to list eagles in adjacent Mexico as endangered. Protected in Canada by the Migratory Bird Treaty and the Wildlife Act. Protected in Mexico by the Migratory Bird Treaty. Many occurrences are protected in wildlife refuges, National, state, and Provincial parks, private nature reserves, and on some TNC-owned property.

Needs: Acquisition of breeding territories is always a priority and is necessary for further improvement. Acquisition of other types of protection of winter foraging habitats and winter roosts advisable.

There is no substantiated evidence that the Bald Eagle has any negative impact. In the past, however, the Bald Eagle has been unjustly accused of hurting both the fish industry and the fur industry. As a result, the governement in Alaska once paid two dollars for every dead eagle brought in. Soon after this went into affect, it became apparent that slaughtering eagles didn't help the fish or fur industry. Another apparently false accusation is that they kill a large number of lambs on open ranges.

Eagles help ranchers by controlling the number of rabbits and rodents -- animals that compete with livestock for grass. Their feathers are used in the ceremonies of some groups of native North Americans.

Comments: Eagle feathers are used for religious and cultural purposes by Native Americans, and the Department of the Interior is responsible for facilitating the distribution of eagle carcasses for these purposes (executive directive, 29 April 1994).

Comments: The two subspecies, Haliaeetus leucocephalus leucocephalus (southern U.S. and Baja California) and H. l. alascanus (northern U.S. and Canada) intergrade broadly in the central and northern U.S. Constitutes a superspecies with H. albicilla (AOU 1998).