The
Bald Eagle is a
bird of preyBirds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
found in
North AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It is the
national bird and symbol of the United States of America. This
sea eagleSea eagle mainly refers to Sea eagle, birds of prey of the genus Haliaeetus.It may also refer to:-Aerospace:* Sea Eagle , British, anti-ship missile* Sea Eagle * Supermarine Sea Eagle, 1920s British passenger flying boat-Sports:...
has two known sub-species and forms a
species pairIn biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each other—but whose morphology is very similar ....
with the
White-tailed EagleThe White-tailed Eagle , also known as the Sea Eagle, Erne , or White-tailed Sea-eagle, is a large bird of prey in the family Accipitridae which includes other raptors such as hawks, kites, and harriers...
. Its range includes most of Canada and
AlaskaAlaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, all of the
contiguous United StatesThe contiguous United States are the 48 U.S. states on the continent of North America that are south of Canada and north of Mexico, plus the District of Columbia....
, and northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting.
The adult Bald Eagle is mainly brown with a white head and tail. The sexes are identical in
plumagePlumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
, but females are larger than males. The
beakThe beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
is large and hooked. The plumage of the immature is brown. Bald Eagles are not actually bald, the name derives from the older meaning of the word, "white headed".
In the late 20th century the Bald Eagle was on the brink of
extirpationLocal extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
in the continental United States, while flourishing in much of Alaska and Canada. Populations recovered and stabilized, so the species was removed from the
U.S. federal government'sThe federal government of the United States is the national government of the constitutional republic of fifty states that is the United States of America. The federal government comprises three distinct branches of government: a legislative, an executive and a judiciary. These branches and...
list of
endangered speciesAn endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
and transferred to the list of
threatened speciesThreatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
on July 12, 1995, and it was removed from the List of Endangered and Threatened Wildlife in the Lower 48 States on June 28, 2007.
Description
The
plumagePlumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
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 dimorphismSexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
is evident in the species in that females are 25 percent larger than males. The beak, feet and
iridesThe iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
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
beakThe beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
is large and hooked, with a yellow
cereThe Cère is a long river in south-western France, left tributary of the Dordogne River. Its source is in the south-western Massif Central, near the mountain Plomb du Cantal...
.
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 EagleThe Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
in that the former has a more protruding head with a larger
beakThe beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
, 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
EagleEagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
has sometimes been considered the largest true raptor in North America (excluding the possibly unrelated
California CondorThe California Condor is a New World vulture, the largest North American land bird. Currently, this condor inhabits only the Grand Canyon area, Zion National Park, and coastal mountains of central and southern California and northern Baja California...
), although the species overlaps in size with the American races of the
Golden EagleThe Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
. It is certainly a large bird, with a body length of 70 –. The wingspan is typically between 1.8 and 2.3 m (5.9 and 7.5 ft) and mass is usually between 2.5 and 7 kg (5.5 and 15.4 lb). Females are about 25 percent larger than males, averaging 5.8 kg (12.8 lb) and against the males' average weight of 4.1 kg (9 lb). The size of the bird varies by location; the smallest specimens are those from
FloridaFlorida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
, 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
AlaskaAlaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, where large females may weigh up to 7.5 kg (16.5 lb) and span 2.44 m (8 ft) across the wings.
Its diet consists mainly of
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, but it is an opportunistic feeder. It hunts fish by swooping down and snatching the fish out of the water with its talons. It is sexually mature at four years or five years of age. The Bald Eagle builds the largest
nestA bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
of any North American bird, up to 4 metres (13.1 ft) deep, 2.5 metres (8.2 ft) wide, and one metric ton (1.1
tonThe short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...
s) in weight.
The call consists of weak chirping whistles, harsher and more shrill from young birds than adults.
The average lifespan of Bald Eagles in the wild is around 20 years, with the oldest living to be about 30. 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.
Taxonomy
A species placed in the genus
Haliaeetus (
sea eagleSea eagle mainly refers to Sea eagle, birds of prey of the genus Haliaeetus.It may also refer to:-Aerospace:* Sea Eagle , British, anti-ship missile* Sea Eagle * Supermarine Sea Eagle, 1920s British passenger flying boat-Sports:...
s) which gets both its common and scientific names from the distinctive appearance of the adult's head.
Bald in the
EnglishEnglish is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
name is derived from the word
piebaldA piebald or pied animal is one that has a spotting pattern of large unpigmented, usually white, areas of hair, feathers, or scales and normally pigmented patches, generally black. The colour of the animal's skin underneath its coat is also pigmented under the dark patches and unpigmented under...
, and refers to the white head and tail feathers and their contrast with the darker body. The scientific name is derived from
Haliaeetus,
New LatinThe term New Latin, or Neo-Latin, is used to describe the Latin language used in original works created between c. 1500 and c. 1900. Among other uses, Latin during this period was employed in scholarly and scientific publications...
for "sea eagle" (from the
Ancient GreekAncient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
haliaetos), and
leucocephalus, Latinized Ancient Greek for "white head," from λευκος
leukos ("white") and κεφαλη
kephale ("head").
The Bald Eagle was one of the many species originally described by
LinnaeusCarl Linnaeus , also known after his ennoblement as , was a Swedish botanist, physician, and zoologist, who laid the foundations for the modern scheme of binomial nomenclature. He is known as the father of modern taxonomy, and is also considered one of the fathers of modern ecology...
in his 18th century work
Systema NaturaeThe book was one of the major works of the Swedish botanist, zoologist and physician Carolus Linnaeus. The first edition was published in 1735...
, under the name
Falco leucocephalus.
There are two recognized
subspeciesSubspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of Bald Eagle:
- H. l. leucocephalus (Linnaeus, 1766) is the nominate subspecies. It is separated from H. l. washingtoniensis at approximately latitude 38° N
The 38th parallel north is a circle of latitude that is 38 degrees north of the Earth's equatorial plane. It crosses Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean...
, or roughly the latitude of San Francisco. It is found in the southern United States and Baja CaliforniaBaja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
.
- 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
The 38th parallel north is a circle of latitude that is 38 degrees north of the Earth's equatorial plane. It crosses Europe, the Mediterranean Sea, Asia, the Pacific Ocean, North America, and the Atlantic Ocean...
on the Atlantic CoastThe East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
, where they occur in the Cape HatterasCape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...
area.
The Bald Eagle forms a species pair with the
EurasiaEurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...
n
White-tailed EagleThe White-tailed Eagle , also known as the Sea Eagle, Erne , or White-tailed Sea-eagle, is a large bird of prey in the family Accipitridae which includes other raptors such as hawks, kites, and harriers...
. 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
MioceneThe Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
(c. 10 Ma BP) at the latest, but possibly as early as the Early/Middle
OligoceneThe Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
, 28 Ma BP, if the most ancient fossil record is correctly assigned to this
genusIn biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. The two species probably diverged in the North
PacificThe Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, 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 kilometres (4 sq mi) are optimal for breeding Bald Eagles.
The Bald Eagle requires old-growth and mature stands of
coniferousThe conifers, division Pinophyta, also known as division Coniferophyta or Coniferae, are one of 13 or 14 division level taxa within the Kingdom Plantae. Pinophytes are gymnosperms. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being...
or
hardwoodHardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
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 (0.745647283979768 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 RiverThe Willamette River is a major tributary of the Columbia River, accounting for 12 to 15 percent of the Columbia's flow. The Willamette's main stem is long, lying entirely in northwestern Oregon in the United States...
in
PortlandPortland is a city located in the Pacific Northwest, near the confluence of the Willamette and Columbia rivers in the U.S. state of Oregon. As of the 2010 Census, it had a population of 583,776, making it the 29th most populous city in the United States...
,
OregonOregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. Despite this sensitivity, a family of Bald Eagles recently moved to the
HarlemHarlem is a neighborhood in the New York City borough of Manhattan, which since the 1920s has been a major African-American residential, cultural and business center. Originally a Dutch village, formally organized in 1658, it is named after the city of Haarlem in the Netherlands...
neighborhood of
ManhattanManhattan is the oldest and the most densely populated of the five boroughs of New York City. Located primarily on the island of Manhattan at the mouth of the Hudson River, the boundaries of the borough are identical to those of New York County, an original county of the state of New York...
in
New York CityNew York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
.
The Bald Eagle's natural range covers most of North America, including most of
CanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, all of the continental United States, and northern
MexicoThe United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. It is the only sea eagle endemic to North America. Occupying varied habitats from the
bayouA bayou is an American term for a body of water typically found in flat, low-lying areas, and can refer either to an extremely slow-moving stream or river , or to a marshy lake or wetland. The name "bayou" can also refer to creeks that see level changes due to tides and hold brackish water which...
s of
LouisianaLouisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
to the
Sonoran DesertThe Sonoran Desert is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest...
and the eastern deciduous forests of
QuebecQuebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
and
New EnglandNew England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...
, northern birds are
migratoryBird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, while southern birds are resident, remaining on their breeding territory all year. At minimum population, in the 1950s, it was largely restricted to
AlaskaAlaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, the
Aleutian Islands, northern and eastern Canada, and
FloridaFlorida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
.
Bald Eagles will also congregate in certain locations in winter. From November until February, one to two thousand birds winter in
Squamish, British ColumbiaSquamish is a community and a district municipality in the Canadian province of British Columbia, located at the north end of Howe Sound on the Sea to Sky Highway...
, about halfway between
VancouverVancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...
and
WhistlerWhistler is a Canadian resort town in the southern Pacific Ranges of the Coast Mountains in the province of British Columbia, Canada, approximately north of Vancouver...
. The birds primarily gather along the
SquamishThe Squamish River is a short but very large river in the Canadian province of British Columbia. Its drainage basin is in size. The total length of the Squamish River is approximately .-Course:...
and
CheakamusThe Cheakamus River is a tributary of the Squamish River, beginning on the west slopes of Outlier Peak in Garibaldi Provincial Park upstream from Cheakamus Lake on the southeastern outskirts of the resort area of Whistler. The river flows into Cheakamus Lake before exiting it and flowing...
Rivers, attracted by the
salmonSalmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
spawning in the area.
It has occurred as a
vagrantVagrancy is a phenomenon in biology whereby individual animals appear well outside their normal range; individual animals which exhibit vagrancy are known as vagrants. The term accidental is sometimes also used...
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
KerryKerry means the "people of Ciar" which was the name of the pre-Gaelic tribe who lived in part of the present county. The legendary founder of the tribe was Ciar, son of Fergus mac Róich. In Old Irish "Ciar" meant black or dark brown, and the word continues in use in modern Irish as an adjective...
on November 15, 1987.
Behavior
The Bald Eagle is a powerful flier, and soars on
thermal convection currentsA thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
. It reaches speeds of 56 – when gliding and flapping, and about 48 kilometres per hour (29.8 mph) while carrying fish. Its dive speed is between 120–160 km/h (74.6–99.4 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. The Bald Eagle selects migration routes which take advantage of
thermalA thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and are an example of convection. The sun warms the ground, which in turn warms the air directly above it...
s, 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.
Diet
The Bald Eagle's diet is opportunistic and varied, but most feed mainly on
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. In the
Pacific NorthwestThe Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
, spawning
troutTrout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
and
salmonSalmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
provide most of the Bald Eagles' diet.
Locally, eagles may rely largely on
carrionCarrion refers to the carcass of a dead animal. Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters include vultures, hawks, eagles, hyenas, Virginia Opossum, Tasmanian Devils, coyotes, Komodo dragons, and burying beetles...
, especially in winter, and they will scavenge carcasses up to the size of
whaleWhale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...
s, though it seems that carcasses of
ungulateUngulates are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving. They make up several orders of mammals, of which six to eight survive...
s and large
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
are preferred. They also may sometimes feed on subsistence scavenged or stolen from campsites and picnics, as well as garbage dumps. Mammalian prey includes
rabbitRabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s,
hareHares and jackrabbits are leporids belonging to the genus Lepus. Hares less than one year old are called leverets. Four species commonly known as types of hare are classified outside of Lepus: the hispid hare , and three species known as red rock hares .Hares are very fast-moving...
s,
raccoonProcyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...
s,
muskratThe muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...
s,
beaverThe beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...
s, and
deerDeer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
fawns. Preferred avian prey includes
grebeA grebe is a member of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter...
s, alcids,
duckDuck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
s,
gullGulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s,
cootCoots are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water...
s,
egretAn egret is any of several herons, most of which are white or buff, and several of which develop fine plumes during the breeding season. Many egrets are members of the genera Egretta or Ardea which contain other species named as herons rather than egrets...
s, and geese. Most live prey are quite a bit smaller than the eagle, but predatory attacks on larger birds such as
swanSwans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...
s have been recorded.
ReptileReptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s,
amphibianAmphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s and
crustaceanCrustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s (especially
crabTrue crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s) are preyed on when available.
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.
OspreyThe Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...
also have this adaptation. Bald Eagles have powerful talons and have been recorded flying with a 15-pound
Mule DeerThe mule deer is a deer indigenous to western North America. The Mule Deer gets its name from its large mule-like ears. There are believed to be several subspecies, including the black-tailed deer...
fawn. 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. Sometimes, if the fish is too heavy to lift, the eagle will be dragged into the water. It may swim to safety, but some eagles drown or succumb to
hypothermiaHypothermia is a condition in which core temperature drops below the required temperature for normal metabolism and body functions which is defined as . Body temperature is usually maintained near a constant level of through biologic homeostasis or thermoregulation...
. When competing for food, eagles will usually dominate other fish-eaters and scavengers, aggressively displacing
mammalMammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s such as
coyoteThe coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
s and
foxFox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es, and birds such as corvids,
gullGulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s,
vultureVulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s and other
raptorBirds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
s. Bald Eagles may be displaced by themselves or by
Golden EagleThe Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
s. Neither species is known to be dominant, and the outcome depends on the individual animal. Occasionally, Bald Eagles will steal fish and other prey away from smaller raptors, such as
OspreyThe Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...
s, a practice known as
kleptoparasitismKleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...
. 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 FalconThe Peregrine Falcon , also known as the Peregrine, and historically as the Duck Hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-gray back, barred white underparts, and a black head and "moustache"...
nest for prey items sustained a concussion from a swooping parent Peregrine, and ultimately died days later from it.
Reproduction
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 metres (13.1 ft) deep, 2.5 metres (8.2 ft) across and weigh 1 tonnes (1.1 ST); one nest in Florida was found to be 6.1 metres (20 ft) deep, 2.9 metres (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. 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 millimetres (2.9 in) long and have a breadth of 55 millimetres (2.2 in).
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
DDTDDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
. Bald Eagles, like many birds of prey, were especially affected by DDT due to
biomagnificationBiomagnification, also known as bioamplification or biological magnification, is the increase in concentration of a substance that occurs in a food chain as a consequence of:* Persistence...
. DDT itself was not lethal to the adult bird, but it interfered with the bird's
calciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
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 statesThe contiguous United States are the 48 U.S. states on the continent of North America that are south of Canada and north of Mexico, plus the District of Columbia....
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 last 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 FederationThe National Wildlife Federation is the United States' largest private, nonprofit conservation education and advocacy organization, with over four million members and supporters, and 48 state and territorial affiliated organizations...
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 TreatyThe Migratory Bird Treaty Act of 1918 , codified at , is a United States federal law, at first enacted in 1916 in order to implement the convention for the protection of migratory birds between the United States and Great Britain...
, 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 EagleThe Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
, 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. stateA U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
with the largest resident population is
AlaskaAlaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, with about 40,000–50,000, with the next highest population the
Canadian provinceThe provinces and territories of Canada combine to make up the world's second-largest country by area. There are ten provinces and three territories...
of
British ColumbiaBritish Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
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 ConcernLeast Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
category on the
IUCN Red ListThe IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
.
In captivity
PermitsThe verb license or grant licence means to give permission. The noun license or licence refers to that permission as well as to the document recording that permission.A license may be granted by a party to another party as an element of an agreement...
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
falconryFalconry is "the taking of wild quarry in its natural state and habitat by means of a trained raptor". There are two traditional terms used to describe a person involved in falconry: a falconer flies a falcon; an austringer flies a hawk or an eagle...
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
falconryFalconry is "the taking of wild quarry in its natural state and habitat by means of a trained raptor". There are two traditional terms used to describe a person involved in falconry: a falconer flies a falcon; an austringer flies a hawk or an eagle...
.
Cultural significance
The Bald Eagle is important in various
Native AmericanThe indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
cultures, and as the national bird of the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
, is prominent in seals and logos, coinage, postage stamps, and other items relating to the
U.S. federal governmentThe federal government of the United States is the national government of the constitutional republic of fifty states that is the United States of America. The federal government comprises three distinct branches of government: a legislative, an executive and a judiciary. These branches and...
.
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 EagleThe Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
, are central to many religious and
spiritualNative American mythology is the body of traditional narratives associated with Native American religion from a mythographical perspective. Native American belief systems include many sacred narratives. Such spiritual stories are deeply based in Nature and are rich with the symbolism of seasons,...
customs among
Native AmericansThe indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as Native Americans...
. Eagles are considered spiritual messengers between gods and humans by some cultures. Many
pow wowPow woW is French musical group. Their biggest hit was "Le Chat" in 1992. Their next single was the French version of song "The Lion Sleeps Tonight", titled "Le lion est mort ce soir".- Albums :* Regagner les plaines...
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'wakwThe Kwakwaka'wakw are an Indigenous group of First Nations peoples, numbering about 5,500, who live in British Columbia on northern Vancouver Island and the adjoining mainland and islands.Kwakwaka'wakw translates as "Those who speak Kwak'wala", describing the collective nations within the area that...
scattered eagle down to welcome important guests. The
ChoctawThe Choctaw are a Native American people originally from the Southeastern United States...
explained that the Bald Eagle, who has direct contact with the upper world of the sun, is a symbol of peace.
During the
Sun DanceThe Sun Dance is a religious ceremony practiced by a number of Native American and First Nations peoples, primarily those of the Plains Nations. Each tribe has its own distinct practices and ceremonial protocols...
, 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"Medicine man" or "Medicine woman" are English terms used to describe traditional healers and spiritual leaders among Native American and other indigenous or aboriginal peoples...
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 lawThe eagle feather law provides many exceptions to federal wildlife laws regarding eagles and other migratory birds to enable Native Americans to continue their traditional practices....
stipulates that only individuals of certifiable Native American ancestry enrolled in a federally recognized tribe are legally authorized to obtain 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 AmendmentThe First Amendment to the United States Constitution is part of the Bill of Rights. The amendment prohibits the making of any law respecting an establishment of religion, impeding the free exercise of religion, abridging the freedom of speech, infringing on the freedom of the press, interfering...
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 RepublicThe Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy, traditionally dated around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and...
, in which eagle imagery was prominent. On June 20, 1782, the
Continental CongressThe Continental Congress was a convention of delegates called together from the Thirteen Colonies that became the governing body of the United States during the American Revolution....
adopted the still-current design for the
Great Seal of the United StatesThe Great Seal of the United States is used to authenticate certain documents issued by the United States federal government. The phrase is used both for the physical seal itself , and more generally for the design impressed upon it...
including a Bald Eagle grasping 13
arrowAn arrow is a shafted projectile that is shot with a bow. It predates recorded history and is common to most cultures.An arrow usually consists of a shaft with an arrowhead attached to the front end, with fletchings and a nock at the other.- History:...
s and a 13-leaf
olive branchThe olive branch in Western culture, derived from the customs of Ancient Greece, symbolizes peace or victory and was worn by brides.-Ancient Greece and Rome:...
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 StatesThe Seal of the President of the United States is used to mark correspondence from the U.S. president to the United States Congress, and is also used as a symbol of the presidency. The central design, based on the Great Seal of the United States, is the official coat of arms of the U.S...
and the
Presidential FlagThe Flag of the President of the United States consists of the presidential coat of arms on a dark blue background. While having the same design as the presidential seal since 1945, the flag has a separate history, and the designs on the flag and seal have at different times influenced each other...
, and in many U.S. federal agency
logoA logo is a graphic mark or emblem commonly used by commercial enterprises, organizations and even individuals to aid and promote instant public recognition...
s. Between 1916 and 1945, the Presidential Flag showed an eagle facing to its left (the viewer's right), which gave rise to the
urban legendAn urban legend, urban myth, urban tale, or contemporary legend, is a form of modern folklore consisting of stories that may or may not have been believed by their tellers to be true...
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 FranklinDr. Benjamin Franklin was one of the Founding Fathers of the United States. A noted polymath, Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat...
ever supported the
Wild TurkeyThe Wild Turkey is native to North America and is the heaviest member of the Galliformes. It is the same species as the domestic turkey, which derives from the South Mexican subspecies of wild turkey .Adult wild turkeys have long reddish-yellow to grayish-green...
, 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 CincinnatiThe Society of the Cincinnati is a historical organization with branches in the United States and France founded in 1783 to preserve the ideals and fellowship of the American Revolutionary War officers and to pressure the government to honor pledges it had made to officers who fought for American...
, and does not mention the choice of the Bald Eagle for the
Great Seal of the United StatesThe Great Seal of the United States is used to authenticate certain documents issued by the United States federal government. The phrase is used both for the physical seal itself , and more generally for the design impressed upon it...
. Franklin opposed the creation of the Society because he viewed it, with its hereditary membership, as a
noble orderAn order or order of merit is a visible honour, awarded by a government, dynastic house or international organization to an individual, usually in recognition of distinguished service to a nation or to humanity. The distinction between orders and decorations is somewhat vague, except that most...
unwelcome in the newly independent
RepublicA republic is a form of government in which the people, or some significant portion of them, have supreme control over the government and where offices of state are elected or chosen by elected people. In modern times, a common simplified definition of a republic is a government where the head of...
, 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.
See also
- Coat of arms of the Philippines
The Coat of Arms of the Philippines features the eight-rayed sun of the Philippines with each ray representing the eight provinces which were placed under martial law by Governor-General Ramón Blanco during the Philippine Revolution, and the three five-pointed stars representing the three primary...
- List of national birds
Identification
- Grant, Peter J. (1988) The Co. Kerry Bald Eagle Twitching 1(12): 379-80 - describes plumage differences between Bald Eagle and White-tailed Eagle in juveniles
External links
Video links