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Overview

Brief Summary

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.

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Distribution

Range Description

This species breeds in Canada, USA, Mexico, and the French island territories of Saint Pierre and Miquelon. It is considered a vagrant in Belize, Bermuda, Ireland, Puerto Rico, and the US Virgin Islands.
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North America
  • North-West Atlantic Ocean species (NWARMS)
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Source: World Register of Marine Species

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North America
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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 )

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National Distribution

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

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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.

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The bald eagle breeds from central Alaska across Canada to Labrador and
Newfoundland and south to southern mainland Alaska and the Aleutian
Islands [29]. 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 [1]. 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
coasts [16].

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Regional Distribution in the Western United States

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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

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Occurrence in North America


AL AK AZ AR CA CO CT DE FL GA
ID IL IN IA KS KY LA ME MD MA
MI MN MS MO MT NE NV NH NJ NM
NY NC ND OH OK OR PA RI SC SD
TN TX UT VT VA WA WV WI WY DC
AB BC MB NB NF NT NS ON PE PQ
SK YK
MEXICO

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Observations

Public Domain

Supplier: Jeff Holmes

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Physical Description

Morphology

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.

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Size

Length: 94 cm

Weight: 5244 grams

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Diagnostic Description

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.

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Ecology

Habitat

Habitat and Ecology

Systems
  • Terrestrial
  • Freshwater
  • Marine
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Depth range based on 2433 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0 - 0
 
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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

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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.

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Cover Requirements

More info for the terms: cover, tree

Habitat suitability index models have been developed for wintering bald
eagles in lacustrine and estuarine habitats of the central and northern
states [25]. Bald eagles need old-growth or late-successional forests
for nesting and roosting [20]. 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 [11]. 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 [25].

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
[13].

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 [16]. 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.

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Preferred Habitat

Bald eagles prefer habitat near seacoasts, rivers, large lakes, and
other large areas of open water [25]. 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 [21]. 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) [25].

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 [25]. 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 [13].

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Associated Plant Communities

More info for the term: cover

See ECOSYSTEMS, PLANT ASSOCIATIONS, and COVER TYPES.

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Habitat: Cover Types

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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
16 Aspen
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
38 Tamarack
40 Post oak - blackjack oak
42 Bur oak
62 Silver maple - American elm
63 Cottonwood
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
217 Aspen
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

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Habitat: Plant Associations

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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
K092 Everglades
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

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Habitat: Ecosystem

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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
FRES11 Spruce-fir
FRES13 Loblolly-shortleaf pine
FRES14 Oak-pine
FRES15 Oak-hickory
FRES17 Elm-ash-cottonwood
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES28 Western hardwoods
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows

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Depth range based on 2433 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 0 - 0
 
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Migration

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).

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Trophic Strategy

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.

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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).

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Food Habits

Bald eagles eat fish, reptiles, birds, mammals, invertebrates and
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].

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Associations

Known prey organisms

Haliaeetus leucocephalus preys on:
Actinopterygii
Aves
Dasyatis sabina
Arius felis
Paralichthyes albigutta
Strongylura marina
Laridae
Cyprinodon variegatus
Bucephala albeaola
Rallus longirostris
Charadrius semipalmatus
Podilymbus podiceps
Pandion haliaetus
Fulica americana
Larus californicus
Asio flammeus
Corvus caurinus
Enhydra lutris

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 winter’s seagrass foodweb network through effective trophic levels. Ecol Model 117:99–124
  • 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).
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Population Biology

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.

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Global Abundance

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.

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General Ecology

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).

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Habitat-related Fire Effects

More info for the terms: fuel, fuel loading, snag, stand-replacing fire

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 [28]. If low-intensity,
litter-reducing fires are not allowed to burn in old-growth forests,
stand-replacing, high-intensity crown fires can result [6].

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 [33].
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 [33]. Old-growth eastern white pine (Pinus
strobus) forests in Ontario continually recruit snags in the absence of
fire because of their uneven-aged structure [32]. Catastrophic fires in
mature and old-growth forests can create even-aged conditions which may
stop continuous snag recruitment [32].

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Timing of Major Life History Events

Mate - late September through November in the South; January through
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]

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Life History and Behavior

Behavior

Perception Channels: visual ; tactile ; acoustic ; chemical

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Cyclicity

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).

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Life Expectancy

Average lifespan

Status: wild:
369 months.

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Lifespan, longevity, and ageing

Maximum longevity: 48 years (captivity) Observations: In the wild, the bald eagle may live over 30 years (http://www.dec.state.ny.us/).
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Reproduction

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.

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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.

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Molecular Biology and Genetics

Molecular Biology

Barcode data: Haliaeetus leucocephalus

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 6 barcode sequences available from BOLD and GenBank.

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.

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNATAGTCGGCACCGCCCTCAGCTTACTCATCCGCGCAGAACTCGGCCAACCAGGCACACTCCTAGGCGACGACCAAATCTACAACGTAGTCGTCACCGCACATGCTTTCGTAATAATCTTCTTCATAGTCATACCTATCATAATCGGAGGATTCGGAAACTGACTTGTTCCACTCATAATTGGCGCCCCCGACATAGCCTTCCCACGCATAAACAACATAAGCTTCTGACTACTTCCTCCCTCCCTCCTCCTCTTACTAGCCTCCTCAACTGTAGAGGCAGGAGCTGGCACCGGATGAACTGTTTATCCCCCATTAGCAGGCAACATAGCCCATGCCGGAGCCTCAGTAGACTTAGCCATCTTCTCCCTACACCTAGCTGGAATCTCATCCATCCTAGGAGCAATTAACTTTATCACAACCGCTATCAACATAAAACCCCCAGCCCTCTCCCAATACCAGACACCCCTATTTGTATGATCCGTTCTCATCACCGCCGTCCTACTACTGCTCTCACTTCCAGTCCTAGCCGCCGGCATCACCATACTACTTACAGATCGAAACCTCAATACAACATTCTTTGACCCCGCTGGTGGAGGTGACCCCATCCTATACCAGCATCTCTTCTGATTCTTCGGACATCCAGAAGTTTACATCCTAATTCTA
-- end --

Download FASTA File

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Statistics of barcoding coverage: Haliaeetus leucocephalus

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 7
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Butchart, S. & Symes, A.

Contributor/s

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be increasing, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

History
  • Least Concern (LC)
  • Least Concern (LC)
  • Least Concern (LC)
  • Lower Risk/least concern (LR/lc)
  • Lower Risk/least concern (LR/lc)
  • Lower Risk/least concern (LR/lc)
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