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 )
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Breeding range extends from 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); breeding is very localized in the Great Basin and prairie and plains regions in interior North America, where the the breeding range recently has expanded to include Nebraska and Kansas. In Arizona, nesting occurs primarily along the Salt and Verde rivers in the central part of the state; only a few pairs nest in the western part of the state (http://www.swbemc.org/nest_sites.html). In Nevada, the few nesting pairs are primarily in the west-central part of the state, with another nesting area in extreme southern Elko County (GBBO 2010).
In the nonbreeding season, bald eagles occur 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.
Newfoundland and south to southern mainland Alaska and the Aleutian
Islands . It also breeds in Baja California, central Arizona,
southwestern and central New Mexico, and along the Gulf Coast from Texas
to Florida [1,29]. The bald eagle occurs only locally throughout much
of the Great Basin and Great Plains . Bald eagles winter in most of
their breeding range, from southern Alaska and Canada southward [1,29].
Resident populations are found along the Atlantic, Pacific, and Gulf
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
Occurrence in North America
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 .
Other Physical Features: endothermic ; bilateral symmetry
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.
Puget Lowland Forests Habitat
Cope's giant salamander is found in the Puget lowland forests along with several other western North America ecoregions. The Puget lowland forests occupy a north-south topographic depression between the Olympic Peninsula and western slopes of the Cascade Mountains, extending from north of the Canadian border to the lower Columbia River along the Oregon border. The portion of this forest ecoregion within British Columbia includes the Fraser Valley lowlands, the coastal lowlands locally known as the Sunshine Coast and several of the Gulf Islands. This ecoregion is within the Nearctic Realm and classified as part of the Temperate Coniferous Forests biome.
The Puget lowland forests have a Mediterranean-like climate, with warm, dry summers, and mild wet winters. The mean annual temperature is 9°C, the mean summer temperature is 15°C, and the mean winter temperature is 3.5°C. Annual precipitation averages 800 to 900 millimeters (mm) but may be as great as 1530 mm. Only a small percentage of this precipitation falls as snow. However, annual rainfall on the San Juan Islands can be as low as 460 mm, due to rain-shadow effects caused by the Olympic Mountains. This local rain shadow effect results in some of the driest sites encountered in the region. Varied topography on these hilly islands results in a diverse assemblage of plant communities arranged along orographically defiined moisture gradients. Open grasslands with widely scattered trees dominate the exposed southern aspects of the islands, while moister dense forests occur on northern sheltered slopes characterized by Western red cedar (Thuja plicata), Grand fir (Abies grandis), and Sword fern (Polystichum munitum) communities.
There are only a small number of amphibian taxa in the Puget lowland forests, namely: Cope's giant salamander (Dicamptodon copei); Monterey ensatina (Ensatina eschscholtzii); Long-toed salamander (Ambystoma macrodactylum); Western redback salamander (Plethodon vehiculum); Northwestern salamander (Ambystoma gracile); Pacific chorus frog (Pseudacris regilla); Coastal giant salamander (Dicamptodon tenebrosus); Rough-skin newt (Taricha granulosa); the Vulnerable Spotted frog (Rana pretiosa); Tailed frog (Ascopus truei); and Northern red-legged frog (Rana aurora).
Likewise there are a small number of reptilian taxa within the ecoregion: Common garter snake (Thamnophis sirtalis); Western terrestrial garter snake (Thamnophis sirtalis); Northern alligator lizard (Elgaria coerulea); Western fence lizard (Sceloporus occidentalis); Northwestern garter snake (Thamnophis ordinoides); Sharp-tailed snake (Contia tenuis); Yellow-bellied racer (Coluber constrictor); and Western pond turtle (Clemmys marmorata).
There are numberous mammalian taxa present in the Puget lowland forests. A small sample of these are:Creeping vole (Microtus oregoni), Raccoon (Procyon lotor), Southern sea otter (Enhydra lutris), Mink (Mustela vison), Coyote (Canis latrans), Black-tailed deer (Odocoileus hemionus), Pallid bat (Antrozous pallidus), and Harbour seal (Phoca vitulina).
A rich assortment of bird species present in this ecoregion, including the Near Threatened Spotted owl (Strix occidentalis), Turkey vulture (Cathartes aura), Bald eagle (Haliaeetus leucocephalus), Blue grouse (Dendragapus obscurus), as well as a gamut of seabirds, numerous shorebirds and waterfowl.
Sierra Juarez and San Pedro Martir pine-oak forests Habitat
This taxon can be found in the Sierra Juarez and San Pedro Martir pine-oak forests. The ecoregion is located in two mountain ranges in the state of Baja California, Mexico: the Sierra de Juarez and the Sierra de San Pedro Martir. Both mountain ranges belong to the physiographical province of Baja California, and constitute the northernmost elevated peaks of the Baja Peninsula. The mountainous range that descends into a large portion of Baja California becomes more abrupt at Juarez and San Pedro Martir; the eastern slope is steeper than the western. Altitudes range between 1100-2800 meters. The granitic mountains of Juarez and San Pedro Martir have young rocky soils and are poorly developed, shallow, and low in organic matter.
Dominant trees in the ecoregion are: Pinus quadrifolia, P. jeffreyi, P. contorta, P. lambertiana, Abies concolor, and Libocedrus decurren. The herbaceous stratum is formed by Bromus sp. and Artemisia tridentata. Epiphytes and fungi are abundant throughout the forests.
Characteristic mammals of the ecoregion include: Ornate shrew (Sorex ornatus), Puma (Puma concolor), Fringed Myotis bat (Myotis thysanodes), California chipmunk (Tamias obscurus), Bobcat (Lynx rufus), Coyote (Canis latrans), San Joaquin kit fox (Vulpes macrotis) and Bighorn sheep (Ovis canadensis).
Numerous birds are present in the ecoregion, including the rare Bald eagle (Haliaeetus leucocephalus), California condor (Gymnogyps californianus), Pinyon jay (Gymnohinus cyanocephalus), and White-breasted nuthatch (Sitta carolinensis).
A number of different reptilian taxa are found in these oak-pine forests; representative reptiles here are: the Banded rock lizard (Petrosaurus mearnsi); Common checkered whiptail (Cnemidophorus tesselatus), who is found in sparsely vegetated areas; Coast horned lizard (Phrynosoma coronatum), often found in locales of sandy soil, where individuals may burrow to escape surface heat; Night desert lizard (Xantusia vigilis), who is often found among bases of yucca, agaves and cacti; and the Baja California spiny lizard (Sceloporus zosteromus).
The Pacific chorus frog (Pseudacris regilla) is an anuran found within the Sierra Juarez and San Pedro Martir pine-oak forests as one of its western North America ecoregions of occurrence. The only other amphibian in the ecoregion is the Western toad (Anaxyrus boreas).
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
Habitat and Ecology
Comments: Breeding habitat most commonly includes areas close to (within 4 km) coastal areas, bays, rivers, lakes, reservoirs, or other bodies of water that reflect the general availability of primary food sources including fish, waterfowl, or seabirds (Andrew and Mosher 1982, Green 1985, Campbell et al. 1990). For example, in Saskatchewan lakes, bald eagle density was positively correlated with abundance of large fishes (Dzus and Gerrard 1993).
Nests usually are in tall trees or on pinnacles or cliffs near water. Tree species used for nesting vary regionally and may include pine, spruce, fir, cottonwood, poplar, willow, sycamore, oak, beech, or others. Ground nesting has been reported on the Aleutian Islands in Alaska, in Canada's Northwest Territories, and in Ohio, Michigan, and Texas. The same nest may be used year after year, or a pair may use alternate nest sites in successive years. See Livingston et al. (1990) for a model of nesting habitat in Maine. See Wood et al. (1989) for characteristics of nesting habitat in Florida (most nests were in live pine trees). In Oregon, most nests were within 1.6 km of water, usually in the largest tree in a 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). In Arizona, recent nests were on cliffs or pinnacles, or in large cottonwoods, willows, sycamores, or ponderosa pines, usually within 1 km of a riparian corridor (J. T. Driscoll, in Corman and Wise-Gervais 2005).
In winter, bald eagles may associate with waterfowl concentrations or congregate in areas with abundant dead fish (Griffin et al. 1982) or other food resources. Wintering areas are commonly associated with open water though in some regions (e.g., Great Basin) some bald eagles use habitats with little or no open water (e.g., montane areas) if upland food resources (e.g. rabbit or deer carrion, livestock afterbirths) are readily available (GBBO 2010). Wintering eagles tend to avoid areas with high levels of nearby human activity (boat traffic, pedestrians) and development (buildings) (Buehler et al. 1991). Bald eagles preferentially roost in conifers or other sheltered sites in winter in some areas; typically they select 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). Communal night roosts often are in trees that are used in successive years.
Habitat suitability index models have been developed for wintering bald
eagles in lacustrine and estuarine habitats of the central and northern
states . Bald eagles need old-growth or late-successional forests
for nesting and roosting . Nest snags must be sturdy to support
nests. Tree height or species is not as important as the abundance of
comparatively large trees near feeding areas . Lakes greater than
3.8 square miles (10 sq km) may be optimal for breeding bald eagles,
although longer and narrower bodies of water can support breeding pairs.
Nest trees should have an open form and sturdy branches in the upper
one-third of the tree. Eagles nest in the overstory. Forests used for
nesting should have a canopy cover of less than 60 percent (may be as
low as 20 percent) and be near water. In treeless areas, bald eagles
nest on cliffs or on the ground .
Roosting sites need not be as near to water as nesting sites. It is
more important that roosting sites are in dense stands of old growth
that offer protection from weather. Eagles usually arrive at roost
sites after dark and depart roost sites before dawn. It is therefore is
difficult to determine important roost sites through daytime observation
Average home ranges for eight pairs of bald eagles in Oregon were 1,650
acres (660 ha), with an average distance between nest territories of 2
miles (3.2 km), and an average of 0.3 miles (0.5 km) of shoreline per
pair . In Arizona, the estimate was 24.6 square miles (64 sq km) of
home range, with 9.4 to 11.2 miles (15-18 km) of shoreline for each pair.
other large areas of open water . They prefer to nest, perch, and
roost primarily in old-growth and mature stands of conifers or
hardwoods. Eagles usually select the oldest and tallest trees that have
good visibility, an open structure, and are near prey [9,11,16,18,26]. A
study in Maine showed a preference for areas with "superdominant" trees.
It also showed bald eagles avoided lakes surrounded by dense forest or
inhabited by cold-water fishes. They used areas away from human
disturbance and selected nesting sites near lakes with an abundance of
warm-water fishes . Another study showed a preference for nesting
near lakes with a circumference greater than 7-mile (11-km). The
smallest body of water supporting a nesting pair of bald eagles was 20
acres (8 ha) .
Eagles choose sites more than 0.75 miles (1.2 km) from low-density human
disturbance and more than 1.2 miles (1.8 km) from medium- to
high-density human disturbance . Wintering bald eagles in New
Mexico and Arizona used a disproportionate amount of snags in the
largest class size (no d.b.h. given) for perching, and usually perched
in the top one-third of these trees. For roosting, eagles preferred
the largest live trees with open structures for visibility .
Associated Plant Communities
See ECOSYSTEMS, PLANT ASSOCIATIONS, and COVER TYPES.
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the term: hardwood
1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce - tamarack
15 Red pine
18 Paper birch
21 Eastern white pine
22 White pine - hemlock
23 Eastern hemlock
30 Red spruce - yellow birch
32 Red spruce
33 Red spruce - balsam fir
34 Red spruce - Fraser fir
35 Paper birch - red spruce - balsam fir
40 Post oak - blackjack oak
42 Bur oak
62 Silver maple - American elm
78 Virginia pine - oak
79 Virginia pine
81 Loblolly pine
82 Loblolly pine - hardwood
105 Tropical hardwoods
107 White spruce
201 White spruce
202 White spruce - paper birch
203 Balsam poplar
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce - subalpine fir
207 Red fir
210 Interior Douglas-fir
211 White fir
212 Western larch
213 Grand fir
215 Western white pine
216 Blue spruce
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
222 Black cottonwood - willow
223 Sitka spruce
224 Western hemlock
225 Western hemlock - Sitka spruce
226 Coastal true fir - hemlock
227 Western redcedar - western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir - western hemlock
234 Douglas-fir - tanoak - Pacific madrone
235 Cottonwood - willow
237 Interior ponderosa pine
238 Western juniper
239 Pinyon - juniper
243 Sierra Nevada mixed conifer
244 Pacific ponderosa pine - Douglas-fir
245 Pacific ponderosa pine
246 California black oak
250 Blue oak - Digger pine
251 White spruce - aspen
252 Paper birch
253 Black spruce - white spruce
254 Black spruce - paper birch
256 California mixed subalpine
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
More info for the term: bog
K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K003 Silver fir - Douglas-fir forest
K004 Fir - hemlock forest
K005 Mixed conifer forest
K008 Lodgepole pine - subalpine forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K013 Cedar - hemlock - pine forest
K014 Grand fir - Douglas-fir forest
K015 Western spruce - fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine - Douglas-fir forest
K019 Arizona pine forest
K020 Spruce - fir - Douglas-fir forest
K021 Southwestern spruce - fir forest
K022 Great Basin pine forest
K023 Juniper - pinyon woodland
K024 Juniper steppe woodland
K029 California mixed evergreen forest
K030 California oakwoods
K034 Montane chaparral
K037 Mountain-mahogany - oak scrub
K038 Great Basin sagebrush
K093 Great Lakes spruce - fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K098 Northern floodplain forest
K101 Elm - ash forest
K103 Mixed mesophytic forest
K106 Northern hardwoods
K107 Northern hardwoods - fir forest
K108 Northern hardwoods - spruce forest
K113 Southern floodplain forest
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES10 White-red-jack pine
FRES13 Loblolly-shortleaf pine
FRES21 Ponderosa pine
FRES22 Western white pine
FRES24 Hemlock-Sitka spruce
FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES36 Mountain grasslands
FRES37 Mountain meadows
Depth range (m): 0 - 0
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
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).
carrion, including that of livestock. Some food species of eagles
include bullhead fish (Ictalurus spp.), alewife (Alosa pseudoharengus),
chain pickerel (Esox niger), sucker (Catostomus spp.), salmon
(Oncorhyncus spp.), white perch (Morone americana), smallmouth bass
(Micropterus dolomieui), eel (Anguilla rostrata), sea otter (Enhydra
lutris), grebe (Podilymbus podiceps), Canada goose (Branta canadensis),
American coot (Fulica americana), mallard (Anas platyrhynchos), pintail
(A. acuta), hare (Lepus spp.), and prairie dog (Cynomys spp.) [17,18,21,25].
Known prey organisms
Based on studies in:
USA: Florida, Everglades (Estuarine)
USA: Florida (Estuarine)
This list may not be complete but is based on published studies.
- Christian RR, Luczkovich JJ (1999) Organizing and understanding a winters seagrass foodweb network through effective trophic levels. Ecol Model 117:99124
- Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed February 16, 2011 at http://animaldiversity.org. http://www.animaldiversity.org
- W. E. Odum and E. J. Heald, The detritus-based food web of an estuarine mangrove community, In Estuarine Research, Vol. 1, Chemistry, Biology and the Estuarine System, Academic Press, New York, pp. 265-286, from p. 281 (1975).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: > 300
Comments: The total number of occupied territories (not equivalent to breeding area occurrences) in British Columbia and Alaska is probably at least 7,000 (Gerrard 1983); there are about 1,000 on Vancouver Island alone (British Columbia CDC 1993). Kjos (1992) estimated there were 3,014 occupied bald eagle territories in the lower 48 states.
100,000 - 1,000,000 individuals
Comments: Gerrard (1983) estimated that Alaska and British Columbia had 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, 1,165; Chesapeake Bay, 235; Pacific states, 861; southeastern states, 722; southwestern states, 27; total, 3,010 (USFWS 1990). In 1992, there were 149 nesting pairs in New England. Rich et al. (2004) estimated the global population at 330,000.
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 United States. About 100-150 bald eagles winter in Nevada; only a few pairs nest in the state (Nevada Department of Wildlife, GBBO 2010). 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).
Habitat-related Fire Effects
Because forest structure (density and height class) determines avian
community composition, changes in forest structure lead to changes in
avian communities [30,31]. A stand-replacing fire will, therefore,
likely change bald eagle use of a forest. Fires that destroy old-growth
forest can reduce eagle populations . If low-intensity,
litter-reducing fires are not allowed to burn in old-growth forests,
stand-replacing, high-intensity crown fires can result .
Fires create snags, which are important perching and nesting sites for
bald eagles. Snags can possibly increase potential for lightning-caused
fire when standing, and when fallen, they increase fuel loading .
These increased potentials may be hazardous in areas where fire control
for maintaining bald eagle populations is necessary. There have been no
studies to determine if the hazards of snags outweigh their benefits to
eagles. Snag attrition rates have been listed for lodgepole pine
forests following fire . Old-growth eastern white pine (Pinus
strobus) forests in Ontario continually recruit snags in the absence of
fire because of their uneven-aged structure . Catastrophic fires in
mature and old-growth forests can create even-aged conditions which may
stop continuous snag recruitment .
Timing of Major Life History Events
March in the central states; late March to early April in
Alaska; can vary with elevation as well as latitude; usually
mate for life
Maturity - 4 to 5 years
Clutch - two eggs
Incubation - 35 days
Fledge - 10 to 12 weeks
Longevity - up to 36 years in captivity [12,16]
Life History and Behavior
Perception Channels: visual ; tactile ; acoustic ; chemical
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).
Status: wild: 369 months.
Lifespan, longevity, and ageing
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.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
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.
Molecular Biology and Genetics
Barcode data: Haliaeetus leucocephalus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
-- end --
Download FASTA File
Statistics of barcoding coverage: Haliaeetus leucocephalus
Public Records: 6
Specimens with Barcodes: 7
Species With Barcodes: 1
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
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding
Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding
NatureServe Conservation Status
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.
the United States and Canada is available at NatureServe, although recent
changes in status may not be included.
U.S. Federal Legal Status
Act of 1962 .
Global Short Term Trend: Relatively stable to increase of 25%
Global Long Term Trend: Relatively stable to decline of 50%
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). Bald eagle numbers in Arizona are now higher than ever recorded (due to intensive management), but nesting habitat is decreasing in the most productive areas, and some areas where eagles began to nest in the 1990s later were abandoned (J. T. Driscoll, in Corman and Wise-Gervais 2005).
Degree of Threat: Medium
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). Bio-accumulated mercury from fish or exposure to other pesticides may interfere with reproduction or cause direct mortality (see GBBO 2010). 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 United States 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).
In Arizona, mortality from shooting, entanglement in monofilament, and heat stress continue to affect population expansion (J. T. Driscoll, in Corman and Wise-Gervais 2005).
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.
Use of Fire in Population Management
Fire can be used to reduce litter build-up, control disease, remove less
vigorous species, and allow more vigorous trees to reach maturity, thus
providing old-growth habitat for bald eagles .
destruction, pesticide use, and poaching [3,8].
In order of increasing ease, bald eagles are flushed from perches,
nests, and foraging areas by human disturbance . They are most
easily disturbed by pedestrian traffic and least disturbed by aircraft.
Establishing buffer zones of 148 to 296 feet (400-800 m) in Oregon and
167 to 592 feet (450-1,600 m) in the Southeast was recommended to
reduce the impact of human disturbance on nesting pairs .
Silvicultural treatments for maintaining eagle habitat in ponderosa pine
(Pinus ponderosa) of various age and structure, subclimax mixed conifer,
Douglas-fir (Pseudotsuga menziesii) , and oak (Quercus lobata; Q.
kelloggii) stands in northeastern California are detailed .
Relevance to Humans and Ecosystems
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).
Stewardship Overview: Conservation strategies in the Great Basin region include the following (GBBO 2010): protection and appropriate management of open water and lowland riparian habitat; in areas near known nest sites, several large trees (especially known nest trees) in proximity to large water bodies with large fish should be left intact; tree removal should be restricted or closely supervised in known winter roost areas; restrict human disturbances and pesticide use near nest sites; manage recreational use of lakes and reservoirs to prevent undue disturbance of nest sites and actively used foraging areas; monitor and, if necessary, manage human disturbance in proximity to winter roost sites. These may be applicable throughout most of the species' range.
The Bald Eagle (Haliaeetus leucocephalus Greek hali = salt, aeetus = eagle, leuco = white, cephalis = head) is a bird of prey found in North America. A sea eagle, it has two known sub-species and forms a species pair with the White-tailed Eagle. Its range includes most of Canada and Alaska, all of the contiguous United States, and northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting.
The Bald Eagle is an opportunistic feeder which subsists mainly on fish, which it swoops down and snatches from the water with its talons. It builds the largest nest of any North American bird, up to 4 meters (13 ft) deep, 2.5 meters (8.2 ft) wide, and one metric ton (1.1 tons) in weight, and reaches sexual maturity at four years or five years of age.
Bald Eagles are not actually bald; the name derives from an older meaning of "white headed". The adult is mainly brown with a white head and tail. The sexes are identical in plumage, but females are larger than males. The beak is large and hooked. The plumage of the immature is brown.
The Bald Eagle is the national bird of the United States of America and appears on its Seal. In the late 20th century it was on the brink of extirpation in the continental United States. Populations recovered and the species was removed from the U.S. federal government's list of endangered species on July 12, 1995 and transferred to the list of threatened species. It was removed from the List of Endangered and Threatened Wildlife in the Lower 48 States on June 28, 2007.
The plumage of an adult Bald Eagle is evenly brown with a white head and tail. The tail is moderately long and slightly wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species in that females are 25 percent larger than males. The beak, feet and irides are bright yellow. The legs are feather-free, and the toes are short and powerful with large talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes. The beak is large and hooked, with a yellow cere.
The plumage of the immature is brown, speckled with white until the fifth (rarely fourth, very rarely third) year, when it reaches sexual maturity. Immature Bald Eagles are distinguishable from the Golden Eagle in that the former has a more protruding head with a larger beak, straighter edged wings which are held flat (not slightly raised) and with a stiffer wing beat, and feathers which do not completely cover the legs.
The Bald Eagle has sometimes been considered the largest true raptor (accipitrid) in North America; the larger California Condor is a New World vulture. However, the Golden Eagle, in its American race, broadly overlaps in body weight and overall size with the Bald Eagle. Additionally, the Bald Eagle's close cousins, the longer-winged but shorter-tailed White-tailed Eagle and the overall larger Steller's Sea Eagle, may rarely vagrate to coastal Alaska from Asia.
A recording of a Bald Eagle at Yellowstone National Park
|Problems listening to this file? See media help.|
The Bald Eagle has a body length of 70–102 centimeters (28–40 in) and typical wingspan between 1.8 and 2.3 m (5.9 and 7.5 ft) and mass is usually between 3 and 6.3 kilograms (6.6 and 14 lb). Females are about 25 percent larger than males, averaging 5.8 kg (13 lb), and against the males' average weight of 4.1 kg (9.0 lb). The size of the bird varies by location and generally corresponds with Bergmann's rule, since the species increases in size further away from the Equator and the tropics. The smallest specimens are those from Florida, where mature males may weigh as little as 2.3 kg (5.1 lb) and have a wingspan of 1.68 m (5.5 ft). The largest eagles are from Alaska, where large females may weigh up to 7.5 kg (17 lb) and span 2.44 m (8.0 ft) across the wings. Among standard linear measurements, the wing chord is 51.5–69 cm (20.3–27 in), the tail is 23–37 cm (9.1–15 in) long, and the tarsus is 8 to 11 cm (3.1 to 4.3 in). The culmen reportedly ranges from 3 to 7.5 cm (1.2 to 3.0 in), while the measurement from the gape to the tip of the bill is 7–9 cm (2.8–3.5 in).
The call consists of weak chirping whistles, harsher and more shrill from young birds than adults.
A species placed in the genus Haliaeetus (sea eagles) which gets both its common and scientific names from the distinctive appearance of the adult's head. Bald in the English name is derived from the word piebald, and refers to the white head and tail feathers and their contrast with the darker body. The scientific name is derived from Haliaeetus, New Latin for "sea eagle" (from the Ancient Greek haliaetos), and leucocephalus, Latinized Ancient Greek for "white head," from λευκος leukos ("white") and κεφαλη kephale ("head").
- H. l. leucocephalus (Linnaeus, 1766) is the nominate subspecies. It is separated from H. l. washingtoniensis at approximately latitude 38° N, or roughly the latitude of San Francisco. It is found in the southern United States and Baja California.
- H. l. washingtoniensis (Audubon, 1827), synonym H. l. alascanus Townsend, 1897, the northern subspecies, is larger than southern nominate leucocephalus. It is found in the northern United States, Canada and Alaska. This subspecies reaches further south than latitude 38° N on the Atlantic Coast, where they occur in the Cape Hatteras area.
The Bald Eagle forms a species pair with the Eurasian White-tailed Eagle. This species pair consists of a white-headed and a tan-headed species of roughly equal size; the White-tailed Eagle also has overall somewhat paler brown body plumage. The pair diverged from other Sea Eagles at the beginning of the Early Miocene (c. 10 Ma BP) at the latest, but possibly as early as the Early/Middle Oligocene, 28 Ma BP, if the most ancient fossil record is correctly assigned to this genus. The two species probably diverged in the North Pacific, as the White-tailed Eagle spread westwards into Eurasia and the Bald Eagle spread eastwards into North America.
Habitat and range
The Bald Eagle prefers habitats near seacoasts, rivers, large lakes, oceans, and other large bodies of open water with an abundance of fish. Studies have shown a preference for bodies of water with a circumference greater than 11 km (7 mi), and lakes with an area greater than 10 square kilometers (4 sq mi) are optimal for breeding Bald Eagles.
The Bald Eagle requires old-growth and mature stands of coniferous or hardwood trees for perching, roosting, and nesting. Selected trees must have good visibility, an open structure, and proximity to prey, but the height or species of tree is not as important as an abundance of comparatively large trees surrounding the body of water. Forests used for nesting should have a canopy cover of no more than 60 percent, and no less than 20 percent, and be in close proximity to water.
The Bald Eagle is extremely sensitive to human activity, and is found most commonly in areas free of human disturbance. It chooses sites more than 1.2 km (0.75 mi) from low-density human disturbance and more than 1.8 km (1.1 mi) from medium- to high-density human disturbance. Occasionally Bald Eagles will venture into large estuaries or secluded groves within major cities, such as Hardtack Island on the Willamette River in Portland, Oregon or John Heinz National Wildlife Refuge at Tinicum in Philadelphia, Pennsylvania. Despite this sensitivity, a family of Bald Eagles moved to the Harlem neighborhood in New York City in 2010.
The Bald Eagle's natural range covers most of North America, including most of Canada, all of the continental United States, and northern Mexico. It is the only sea eagle endemic to North America. Occupying varied habitats from the bayous of Louisiana to the Sonoran Desert and the eastern deciduous forests of Quebec and New England, northern birds are migratory, while southern birds are resident, remaining on their breeding territory all year. At minimum population, in the 1950s, it was largely restricted to Alaska, the Aleutian Islands, northern and eastern Canada, and Florida.
Bald Eagles will also congregate in certain locations in winter. From November until February, one to two thousand birds winter in Squamish, British Columbia, about halfway between Vancouver and Whistler. The birds primarily gather along the Squamish and Cheakamus Rivers, attracted by the salmon spawning in the area.
It has occurred as a vagrant twice in Ireland; a juvenile was shot illegally in Fermanagh on January 11, 1973 (misidentified at first as a White-tailed Eagle), and an exhausted juvenile was captured in Kerry on November 15, 1987.
The Bald Eagle is a powerful flier, and soars on thermal convection currents. It reaches speeds of 56–70 kilometers per hour (35–43 mph) when gliding and flapping, and about 48 kilometers per hour (30 mph) while carrying fish. Its dive speed is between 120–160 kilometers per hour (75–99 mph), though it seldom dives vertically. It is partially migratory, depending on location. If its territory has access to open water, it remains there year-round, but if the body of water freezes during the winter, making it impossible to obtain food, it migrates to the south or to the coast. A number of populations are subject to post-breeding dispersal, mainly in juveniles; Florida eagles, for example, will disperse northwards in the summer. The Bald Eagle selects migration routes which take advantage of thermals, updrafts, and food resources. During migration, it may ascend in a thermal and then glide down, or may ascend in updrafts created by the wind against a cliff or other terrain. Migration generally takes place during the daytime, when thermals are produced by the sun.
Locally, eagles may rely largely on carrion, especially in winter. They will scavenge carcasses up to the size of whales, though it seems that carcasses of ungulates and large fish are preferred. They also may sometimes feed on subsistence scavenged or stolen from campsites and picnics, as well as garbage dumps. Mammalian prey includes rabbits, hares, raccoons, muskrats, beavers, and deer fawns. Preferred avian prey includes grebes, alcids, ducks, gulls, coots, egrets, and geese. Bald Eagles have been recorded killing other raptors, even the formidable Great Horned Owls. If a Bald Eagle flies close by, water birds will often fly away en masse, though in other cases they may seemingly ignore a perched eagle. Birds occasionally may be attacked in flight, with prey up to the size of Canada Geese grabbed and killed in mid-air. Unprecedented photographs of a Bald Eagle unsuccessfully attempting to predate a much larger adult Trumpeter Swan in mid-flight were taken recently. Much of the live prey that Bald Eagles catch are quite a bit smaller than the eagle, but predation has been recorded for animals up to the size of mature swans, adult raccoons and young ungulates, all of which are heavier than Bald Eagles. In the Chesapeake Bay area, bald eagles are reportedly the main natural predators of raccoons. Reptiles, amphibians and crustaceans (especially crabs) are preyed upon when available. Occasionally, Bald Eagles may hunt cooperatively, with one bird distracting potential prey, while the other comes behind it in order to ambush it.
To hunt fish, easily their most important live prey, the eagle swoops down over the water and snatches the fish out of the water with its talons. They eat by holding the fish in one claw and tearing the flesh with the other. Eagles have structures on their toes called spicules that allow them to grasp fish. Osprey also have this adaptation. Bald Eagles have powerful talons and have been recorded flying with a 6.8 kg (15 lb) Mule Deer fawn. This feat is the record for the heaviest load carrying ever verified for a flying bird. It has been estimated that the gripping power (pounds by square inch) of the bald eagle is ten times greater than that of a human. Bald eagles can fly with fish at least equal to their own weight, but if the fish is too heavy to lift, the eagle may be dragged into the water. It may swim to safety, but some eagles drown or succumb to hypothermia. When competing for food, eagles will usually dominate other fish-eaters and scavengers, aggressively displacing mammals such as coyotes and foxes, and birds such as corvids, gulls, vultures and other raptors. Bald Eagles may be displaced by themselves or by Golden Eagles. Neither species is known to be dominant, and the outcome depends on the individual animal. In New Jersey during winter, a Golden Eagle and numerous Bald Eagles were observed to hunt Snow Geese alongside each other without conflict. Occasionally, Bald Eagles will steal fish and other prey away from smaller raptors, such as Ospreys and Peregrine Falcons, a practice known as kleptoparasitism. Healthy adult Bald Eagles are not preyed on in the wild and are thus considered apex predators. In one case, an adult eagle investigating a Peregrine Falcon nest for prey items sustained a concussion from a swooping parent Peregrine, and ultimately died days later from it.
Bald Eagles are sexually mature at four or five years of age. When they are old enough to breed, they often return to the area where they were born. It is thought that Bald Eagles mate for life. However, if one member of a pair dies or disappears, the other will choose a new mate. A pair which has repeatedly failed in breeding attempts may split and look for new mates. Bald Eagle courtship involves elaborate calls and flight displays. The flight includes swoops, chases, and cartwheels, in which they fly high, lock talons, and free fall, separating just before hitting the ground. The nest is the largest of any bird in North America; it is used repeatedly over many years and with new material added each year may eventually be as large as 4 meters (13 ft) deep, 2.5 meters (8.2 ft) across and weigh 1 metric ton (1.1 short tons); one nest in Florida was found to be 6.1 meters (20 ft) deep, 2.9 meters (9.5 ft) across, and to weigh 3 short tons (2.7 t). This nest is on record as the largest tree nest ever known for any animal. The nest is built out of branches, usually in large trees near water. When breeding where there are no trees, the Bald Eagle will nest on the ground. Eagles produce between one and three eggs per year, but it is rare for all three chicks to successfully fly. Both the male and female take turns incubating the eggs. The other parent will hunt for food or look for nesting material. The eggs average about 73 millimeters (2.9 in) long and have a breadth of 55 millimeters (2.2 in).
The average lifespan of Bald Eagles in the wild is around 20 years, with the oldest confirmed one having been 28 years of age. In captivity, they often live somewhat longer. In one instance, a captive individual in New York lived for nearly 50 years. As with size, the average lifespan of an eagle population appears to be influenced by its location.
Relationship with humans
Population decline and recovery
Once a common sight in much of the continent, the Bald Eagle was severely affected in the mid-20th century by a variety of factors, among them the thinning of egg shells attributed to use of the pesticide DDT. Bald Eagles, like many birds of prey, were especially affected by DDT due to biomagnification. DDT itself was not lethal to the adult bird, but it interfered with the bird's calcium metabolism, making the bird either sterile or unable to lay healthy eggs. Female eagles laid eggs that were too brittle to withstand the weight of a brooding adult, making it nearly impossible for the eggs to hatch. It is estimated that in the early 18th century, the Bald Eagle population was 300,000–500,000, but by the 1950s there were only 412 nesting pairs in the 48 contiguous states of the US. Other factors in Bald Eagle population reductions were a widespread loss of suitable habitat, as well as both legal and illegal shooting. In 1930 a New York City ornithologist wrote that in the state of Alaska in the previous 12 years approximately 70,000 Bald Eagles had been shot. Many of the hunters killed the Bald Eagles under the long-held mistaken beliefs that Bald Eagles grabbed young lambs and even children with their talons. Later illegal shooting was described as "the leading cause of direct mortality in both adult and immature bald eagles," according to a 1978 report in the Endangered Species Technical Bulletin. In 1984, the National Wildlife Federation listed hunting, power-line electrocution, and collisions in flight as the leading causes of eagle deaths. Bald Eagle populations have also been negatively affected by oil, lead, and mercury pollution, and by human and predator intrusion.
The species was first protected in the U.S. and Canada by the 1918 Migratory Bird Treaty, later extended to all of North America. The 1940 Bald Eagle Protection Act in the U.S., which protected the Bald Eagle and the Golden Eagle, prohibited commercial trapping and killing of the birds. The Bald Eagle was declared an endangered species in the U.S. in 1967, and amendments to the 1940 act between 1962 and 1972 further restricted commercial uses and increased penalties for violators. Also in 1972, DDT was banned in the United States. DDT was completely banned in Canada in 1989, though its use had been highly restricted since the late 1970s.
With regulations in place and DDT banned, the eagle population rebounded. The Bald Eagle can be found in growing concentrations throughout the United States and Canada, particularly near large bodies of water. In the early 1980s, the estimated total population was 100,000 individuals, with 110,000–115,000 by 1992; the U.S. state with the largest resident population is Alaska, with about 40,000–50,000, with the next highest population the Canadian province of British Columbia with 20,000–30,000 in 1992.
It was officially removed from the U.S. federal government's list of endangered species on July 12, 1995, by the U.S. Fish & Wildlife Service, when it was reclassified from "Endangered" to "Threatened." On July 6, 1999, a proposal was initiated "To Remove the Bald Eagle in the Lower 48 States From the List of Endangered and Threatened Wildlife." It was de-listed on June 28, 2007. It has also been assigned a risk level of Least Concern category on the IUCN Red List. In the Exxon Valdez Oil Spill of 1989 an estimated 247 were killed in Prince William Sound, though the local population returned to its pre-spill level by 1995.
Permits are required to keep Bald Eagles in captivity in the United States. Permits are primarily issued to public educational institutions, and the eagles which they show are permanently injured individuals which cannot be released to the wild. The facilities where eagles are kept must be equipped with adequate caging and facilities, as well as workers experienced in the handling and care of eagles. Bald Eagles cannot legally be kept for falconry in the United States. As a rule, the Bald Eagle is a poor choice for public shows, being timid, prone to becoming highly stressed, and unpredictable in nature. Native American Tribes can obtain a "Native American Religious Use" permit to keep non-releasable eagles as well. They use their naturally molted feathers for religious and cultural ceremonies. The Bald Eagle can be long-lived in captivity if well cared for, but does not breed well even under the best conditions. In Canada, a license is required to keep Bald Eagles for falconry.
The Bald Eagle is important in various Native American cultures, and as the national bird of the United States, is prominent in seals and logos, coinage, postage stamps, and other items relating to the U.S. federal government.
Role in Native American culture
The Bald Eagle is a sacred bird in some North American cultures, and its feathers, like those of the Golden Eagle, are central to many religious and spiritual customs among Native Americans. Eagles are considered spiritual messengers between gods and humans by some cultures. Many pow wow dancers use the eagle claw as part of their regalia as well. Eagle feathers are often used in traditional ceremonies, particularly in the construction of regalia worn and as a part of fans, bustles and head dresses. The Lakota, for instance, give an eagle feather as a symbol of honor to person who achieves a task. In modern times, it may be given on an event such as a graduation from college. The Pawnee considered eagles as symbols of fertility because their nests are built high off the ground and because they fiercely protect their young. The Kwakwaka'wakw scattered eagle down to welcome important guests. The Choctaw explained that the Bald Eagle, who has direct contact with the upper world of the sun, is a symbol of peace.
During the Sun Dance, which is practiced by many Plains Indian tribes, the eagle is represented in several ways. The eagle nest is represented by the fork of the lodge where the dance is held. A whistle made from the wing bone of an eagle is used during the course of the dance. Also during the dance, a medicine man may direct his fan, which is made of eagle feathers, to people who seek to be healed. The medicine man touches the fan to the center pole and then to the patient, in order to transmit power from the pole to the patient. The fan is then held up toward the sky, so that the eagle may carry the prayers for the sick to the Creator.
Current eagle feather law stipulates that only individuals of certifiable Native American ancestry enrolled in a federally recognized tribe are legally authorized to obtain or possess Bald or Golden Eagle feathers for religious or spiritual use. The constitutionality of these laws has been questioned by Native American groups on the basis that it violates the First Amendment by affecting ability to practice their religion freely.
National bird of the United States
The Bald Eagle is the national bird of the United States of America. The founders of the United States were fond of comparing their new republic with the Roman Republic, in which eagle imagery was prominent. On June 20, 1782, the Continental Congress adopted the still-current design for the Great Seal of the United States including a Bald Eagle grasping 13 arrows and a 13-leaf olive branch with its talons.
The Bald Eagle appears on most official seals of the U.S. government, including the Seal of the President of the United States and the Presidential Flag, and in many U.S. federal agency logos. Between 1916 and 1945, the Presidential Flag showed an eagle facing to its left (the viewer's right), which gave rise to the urban legend that the seal is changed to have the eagle face towards the olive branch in peace, and towards the arrows in wartime. Contrary to popular legend, there is no evidence that Benjamin Franklin ever publically supported the Wild Turkey, rather than the Bald Eagle, as a symbol of the United States. The origin of this claim is a letter Franklin wrote to his daughter in 1784 from Paris. However, this letter was a criticism of the Society of the Cincinnati in which he stated his personal distaste for the Bald Eagle's behavior but he does not mention publically disputing the choice of the Bald Eagle for the Great Seal of the United States. In the letter Franklin states:
For my own part. I wish the Bald Eagle had not been chosen the Representative of our Country. He is a Bird of bad moral Character. He does not get his Living honestly...Besides he is a rank Coward: The little King Bird not bigger than a Sparrow attacks him boldly and drives him out of the District.
Franklin opposed the creation of the Society because he viewed it, with its hereditary membership, as a noble order unwelcome in the newly independent Republic, contrary to the ideals of Lucius Quinctius Cincinnatus, for whom the Society was named; his reference to the two kinds of birds is interpreted as a satirical comparison between the Society of the Cincinnati and Cincinnatus.
- BirdLife International (2012). "Haliaeetus leucocephalus". IUCN Red List of Threatened Species. Version 2012.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/106003365. Retrieved 16 July 2012.
- del Hoyo, J., Elliott, A., & Sargatal, J., eds. (1994). Handbook of the Birds of the World Vol. 2. Lynx Edicions, Barcelona ISBN 84-87334-15-6.
- Harris. "Bald Eagle Haliaeetus leucocephalus". University of Michigan Museum of Geology. Archived from the original on 4 June 2007. http://animaldiversity.ummz.umich.edu/site/accounts/information/Haliaeetus_leucocephalus.html. Retrieved 2007-06-21.
- "Bald Eagle, Haliaeetus leucocephalus". Cornell Lab of Ornithology. Archived from the original on 2 June 2007. http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Bald_Eagle_dtl.html. Retrieved 2007-06-21.
- Sibley, D. (2000). The Sibley Guide to Birds. National Audubon Society ISBN 0-679-45122-6 p. 127
- Ferguson-Lees, J.; Christie, D. (2001). Raptors of the World. London: Christopher Helm. pp. 717–19. ISBN 0-7136-8026-1.
- Bird, D.M. (2004). The Bird Almanac: A Guide to Essential Facts and Figures of the World's Birds. Ontario: Firefly Books. ISBN 1-55297-925-3.
- "Bald Eagle Facts and Information". Eagles.org. Archived from the original on July 30, 2008. http://web.archive.org/web/20080730055210/http://www.eagles.org/moreabout.html. Retrieved 2008-11-03.
- "ARKive- Bald Eagle video, photos and facts". ARKive.org- Images of Life on Earth. http://www.arkive.org/bald-eagle/haliaeetus-leucocephalus/#text=Facts. Retrieved 2012-07-20.
- Schempf, P. R (1997). "Bald eagle longevity record from Southeastern Alaska". Journal of Field Ornithology 68 (1): 150–51. http://elibrary.unm.edu/sora/JFO/v068n01/p0150-p0151.pdf.
- Dudley, Karen (1998). Bald Eagles. Raintree Steck-Vaughn Publishers. p. 7. ISBN 0-8172-4571-5.
- Joshua Dietz. "What's in a Name". Smithsonian National Zoological Park. Archived from the original on 5 August 2007. http://nationalzoo.si.edu/Animals/Whats_in_a_name/default.cfm?id=19. Retrieved 2007-08-19.
- Liddell, Henry George and Robert Scott (1980). A Greek-English Lexicon (Abridged Edition). United Kingdom: Oxford University Press. ISBN 0-19-910207-4.
- (Latin) Linnaeus, Carolus (1766). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata.. Holmiae. (Laurentii Salvii)..
- "Haliaeetus leucocephalus". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=175420. Retrieved 2007-06-21.
- "Bald Eagle Haliaeetus leucocephalus". The Pacific Wildlife Foundation. Archived from the original on 4 July 2007. http://www.pwlf.org/baldeagle.htm. Retrieved 2007-06-27.
- Brown, N. L.. "Bald Eagle Haliaeetus leucocephalus". Endangered Species Recovery Program. http://web.archive.org/web/20060912000326/http://esrpweb.csustan.edu/speciesprofiles/profile.php?sp=hale. Retrieved 2007-08-20.
- Wink, M (1996). "A mtDNA phylogeny of sea eagles (genus Haliaeetus) based on nucleotide sequences of the cytochrome b gene" (PDF). Biochemical Systematics and Ecology 24 (7–8): 783–791. doi:10.1016/S0305-1978(97)81217-3. Archived from the original on 29 October 2008. http://www.uni-heidelberg.de/institute/fak14/ipmb/phazb/pubwink/1996/20_1996.pdf. Retrieved 2008-11-07.
- "Bald Eagle Habitat". Bald-Eagles.info. http://www.bald-eagles.info/habitat.php. Retrieved 2007-06-21.
- "Wildlife Species: Haliaeetus leucocephalus". USDA Forest Service. http://www.fs.fed.us/database/feis/animals/bird/hale/all.html. Retrieved 2007-06-21.
- "Ross Island FAQ". Willamette Riverkeeper website. Willamette Riverkeeper. 2009. http://www.willamette-riverkeeper.org/documents/RossIslandFactSheet.pdf. Retrieved 2009-11-07.
- "Bald eagles make nest in Heinz Wildlife Refuge". Delaware Daily Times website. Delaware Daily Times. 2010. http://www.delcotimes.com/articles/2010/04/13/news/doc4bc3e624af48b301512385.txt. Retrieved 2012-02-21.
- Carlson, Jen (2010-02-05). "Bald Eagle Spotted Near Fairway". Gothamist. http://gothamist.com/2010/02/05/bald_eagle_1.php. Retrieved 2010-03-20.
- Bull J, Farrand, J Jr (1987). Audubon Society Field Guide to North American Birds: Eastern Region. New York: Alfred A. Knopf. pp. 468–9. ISBN 0-394-41405-5.
- Hope Rutledge. "Where to View Bald Eagles". http://www.baldeagleinfo.com/eagle/eagle1.html. Retrieved 2007-08-20.
- Terres, J. K. (1980). The Audubon Society Encyclopedia of North American Birds. New York, NY: Knopf. pp. 644–646. ISBN 0-394-46651-9.
- "Bald Eagle Facts and Information". Eagles.org. 2007-06-28. Archived from the original on July 30, 2008. http://web.archive.org/web/20080730055210/http://www.eagles.org/moreabout.html. Retrieved 2009-03-03.
- "Bald Eagle: Life History and Habitat". myfwc.com. 2009-4-28. http://myfwc.com/wildlifehabitats/managed/bald-eagle/information/biology/. Retrieved 2012-10-13.
- "Bald Eagle Fact Sheet, Lincoln Park Zoo". Lpzoo.org. Retrieved on 2012-08-22.
- Daum, David W.. "Bald Eagle". Alaska Department of Fish & Game. Archived from the original on 19 August 2007. http://www.adfg.state.ak.us/pubs/notebook/bird/eagles.php. Retrieved 2007-08-15.
- Ferguson-Lees, J.; Christie, D. (2001). Raptors of the World. London: Christopher Helm. ISBN 0-7136-8026-1.
- News | Ohs & Mclane. Ohsmclane.wpengine.com (2012-06-07). Retrieved on 2012-08-22.
- Bald Eagle attacking a Trumpter Swan. Utahbirds.org. Retrieved on 2012-08-21.
- "Birds of North America Online". Bna.birds.cornell.edu. http://bna.birds.cornell.edu/bna/species/506/articles/foodhabits. Retrieved 2012-06-27.
- "Birds of prey — Diet & Eating Habits". Seaworld.org. Archived from the original on 7 February 2009. http://www.seaworld.org/animal-info/info-books/raptors/diet.htm. Retrieved 2009-03-03.
- "Amazing Bird Records". Trails.com. http://www.trails.com/arts/amazing-bird-records.aspx. Retrieved 2012-07-20.
- "Gripping Strength of an Eagle – Understanding psi 101". Hawkquest. http://www.hawkquest.org/TA/XL/Gripping.pdf. Retrieved 2012-07-20.
- School of Birding Workshops. Njaudubon.org. Retrieved on 2012-08-22.
- Jorde, D.G. (1998). "Kleptoparasitism by Bald Eagles wintering in South-Central Nebraska" (PDF). Journal of Field Ornithology 59 (2): 183–188. Archived from the original on 10 August 2007. http://elibrary.unm.edu/sora/JFO/v059n02/p0183-p0188.pdf. Retrieved 2007-08-21.
- Dick Dekker, Marinde Out, Miechel Tabak and Ronald Ydenberg (2012). "The Effect of Kleptoparasitic Bald Eagles and Gyrfalcons on the Kill Rate of Peregrine Falcons Hunting Dunlins Wintering in British Columbia". The Condor 114 (2): 290–294. doi:10.1525/cond.2012.110110. JSTOR 10.1525/cond.2012.110110.
- "San Diego Zoo's Animal Bytes: Bald Eagle". Sandiegozoo.org. Archived from the original on 1 February 2009. http://www.sandiegozoo.org/animalbytes/t-bald_eagle.html. Retrieved 2009-03-03.
- "Cornell University". Bna.birds.cornell.edu. http://bna.birds.cornell.edu/bna/species/660/articles/behavior. Retrieved 2010-03-20.
- R.F. Stocek. "Bald Eagle". Canadian Wildlife Service. Archived from the original on 2007-07-03. http://web.archive.org/web/20070703042651/http://www.hww.ca/hww2.asp?id=27. Retrieved 2007-08-19.
- "Bald Eagle (Haliaeetus leucocephalus)". Michigan Department of Natural Resources. Archived from the original on 10 March 2007. http://www.michigan.gov/dnr/0,1607,7-153-10370_12145_12202-32581--,00.html. Retrieved 2007-04-24.
- Erickson, L. (2007). "Bald Eagle, About Bald Eagle Nests". Journey North. http://www.learner.org/jnorth/tm/eagle/NestAbout1.html.
- Amazing Bird Records. Trails.com (2010-07-27). Retrieved on 2012-08-22.
- "Bald Eagle Fact Sheet". Southern Ontario Bald Eagle Monitoring Project. http://www.bsc-eoc.org/regional/oneaglefacts.html. Retrieved 2008-06-30.
- Brown, Leslie (1976). Birds of Prey: Their biology and ecology. Hamlyn. p. 226. ISBN 0-600-31306-9.
- "Bald Eagle Facts and Information". American eagle foundation. Archived from the original on December 6, 2007. http://web.archive.org/web/20071206030939/http://www.eagles.org/moreabout.html. Retrieved 2008-01-03.
- "American Bald Eagle Is Near Extinction." Popular Science Monthly, March 1930, p. 62.
- Milloy, Steven (2006-07-06). "Bald Eagle". Fox News. Archived from the original on 18 January 2008. http://www.foxnews.com/story/0,2933,202447,00.html. Retrieved 2008-01-03.
- EPA press release (1972-12-31). "DDT Ban Takes Effect". United States Environmental Protection Agency. Archived from the original on 2007-07-05. http://web.archive.org/web/20070705201903/http://www.epa.gov/history/topics/ddt/01.htm. Retrieved 2007-08-22.
- Barrera, Jorge (2005-07-04). "Agent Orange has left deadly legacy Fight continues to ban pesticides and herbicides across Canada". http://web.archive.org/web/20080124123943/http://www.nben.ca/environews/media/mediaarchives/05/july/legacy.htm. Retrieved 2007-08-22.
- "Bald Eagle Soars Off Endangered Species List". U.S. Department of the Interior. 2007-06-28. Archived from the original on July 13, 2007. http://web.archive.org/web/20070713141429/http://www.doi.gov/news/07_News_Releases/070628.html. Retrieved 2007-08-27.
- Maestrelli, John R. (March 1975). "Breeding Bald Eagles in Captivity". The Wilson Bulletin 87 (I): 45–53. http://elibrary.unm.edu/sora/Wilson/v087n01/p0045-p0053.pdf. Retrieved 2007-08-19.
- Fish and Wildlife Conservation Act, 1997. Ministry of Attorney General. http://www.search.e-laws.gov.on.ca/en/isysquery/ca733c6b-d473-44df-952a-203eb9829bcd/4/frame/?search=browseStatutes&context=. Retrieved 2007-11-07.
- Julie Collier. "The Sacred Messengers". Mashantucket Pequot Museum. http://www.pequotmuseum.org/Home/CrossPaths/CrossPathsSpring2003/TheSacredMessengers.htm. Retrieved 2007-05-20.
- Melmer, David (2007-06-11). "Bald eagles may come off threatened list". Indian Country Today. Archived from the original on September 24, 2007. http://web.archive.org/web/20070924211819/http://indiancountry.com/content.cfm?id=1096415182. Retrieved 2007-08-23.
- Brown, Steven C; Averill, Lloyd J.. "Sun Dogs and Eagle Down". University of Washington Press. http://www.washington.edu/uwpress/search/books/BROSUN.html. Retrieved 2007-08-23.
- O'Brien, Greg (2005) [2002, 2005]. "Power Derived from the Outside World". Choctaws in a Revolutionary Age, 1750–1830. University of Nebraska Press. p. 58. ISBN 0-8032-8622-8.
- Lawrence, Elizabeth Atwood. "The Symbolic Role of Animals in the Plains Indian Sun Dance". University of Washington Press. Archived from the original on July 16, 2007. http://web.archive.org/web/20070716065757/http://www.psyeta.org/sa/sa1.1/lawrence.html. Retrieved 2007-08-23.
- DeMeo, Antonia M. (1995). "Access to Eagles and Eagle Parts: Environmental Protection v. Native American Free Exercise of Religion". Hastings Constitutional Law Quarterly 22 (3): 771–813. Archived from the original on 28 September 2007. http://www.animallaw.info/articles/ar22hstclq771.htm. Retrieved 2007-08-22.
- Boradiansky, Tina S. (1990). "Conflicting Values: The Religious Killing of Federally Protected Wildlife". University of New Mexico School of Law. Archived from the original on 7 August 2007. http://www.animallaw.info/articles/arus30nrj709.htm. Retrieved 2007-08-23.
- Lawrence, E.A. (1990). "Symbol of a Nation: The Bald Eagle in American Culture". The Journal of American Culture 13 (1): 63–69. doi:10.1111/j.1542-734X.1990.1301_63.x.
- "Original Design of the Great Seal of the United States (1782)". National Archives. http://www.ourdocuments.gov/doc.php?flash=true&doc=5. Retrieved 2007-08-19.
- The official description was in text only; no diagram was included. Text of the Act.
- 4 U.S.C. § 41; The Bald Eagle on the Great Seal.
- Mikkelson, Barbara & Mikkelson, David P. "A Turn of the Head". snopes.com. http://www.snopes.com/history/american/turnhead.htm. Retrieved 2007-08-19.
- "American Heraldry Society | MMM / The Arms of the United States: Benjamin Franklin and the Turkey". Americanheraldry.org. 2007-05-18. http://americanheraldry.org/pages/index.php?n=MMM.Turkey. Retrieved 2010-03-20.
- Beans, Bruce E. (1996). Eagle's Plume: The Struggle to Preserve the Life and Haunts of America's Bald Eagle. New York, NY: Scribner. ISBN 0-684-80696-7. OCLC 35029744.
- Gerrard, Jonathan M.; Bortolotti, Gary R. (1988). The Bald Eagle: Haunts and Habits of a Wilderness Monarch. Washington, DC: Smithsonian Institution Press. ISBN 0-87474-451-2. OCLC 16801779.
- Isaacson, Philip M. (1975). The American Eagle (1st ed.). Boston, MA: New York Graphic Society. ISBN 0-8212-0612-5. OCLC 1366058.
- Knight, Richard L.; Gutzwiller, Kevin J. (1995). Wildlife and Recreationists: Coexistence through Management and Research. Washington, DC: Island Press. ISBN 1-55963-257-7. OCLC 30893485.
- Laycock, George (1973). Autumn of the Eagle. New York. NY: Scribner. ISBN 0-684-13413-6. OCLC 754345.
- Petersen, Shannon (2002). Acting for Endangered Species: The Statutory Ark. Lawrence, KS: University Press of Kansas. ISBN 0-7006-1172-X. OCLC 48477567.
- Spencer, Donald A. (1976). Wintering of the Migrant Bald Eagle in the Lower 48 States. Washington, DC: National Agricultural Chemicals Association. OCLC 2985418.
- Stalmaster, Mark V. (1987). The Bald Eagle. New York, NY: Universe Books. ISBN 0-87663-491-9. OCLC 15014825.
- Temple, Stanley A. (1978). Endangered Birds: Management Techniques for Preserving Threatened Species. Madison, WI: University of Wisconsin Press. ISBN 0-299-07520-6. OCLC 3750666.
Names and Taxonomy
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).