| Copyright© 2002 Cornell Laboratory of Ornithology |
| Golden Eagle (Aquila chrysaetos) |
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Cool fact: Golden Eagle nests can become huge when material is added to reused nests. One exceptional nest measured 18 feet deep.
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Golden Eagles hunt from the air, soaring at great heights and stooping
at high speed with folded wings or quartering low over the ground and
surprising their victims. Prey species vary regionally, but small- to
medium-sized mammals make up between 70 percent and 98 percent of the
diet. In the semi-arid West, jackrabbits are the primary prey, but in
northern regions, ground squirrels and marmots predominate. Golden Eagles
also hunt young otters and foxes, crows, magpies, grouse and waterfowl.
Occasionally they eat reptiles or fish. Prior to 1962 when Golden Eagles
gained legal protection, thousands were killed in the West under the
mistaken belief that they were a threat to young sheep. Although Golden
Eagles are capable of killing young sheep or other ungulates, such predation
is very rare, and an insignificant cause of sheep mortality. Eagles
are frequently observed scavenging carrion, including sheep.
Young birds attain adult plumage when they are four or five years
old. Subadult Golden Eagles breed only rarely. The same mates apparently
breed together year after year. Golden Eagle pairs maintain an extensive
home range and perform spectacular undulating flights at the edges of
their territories or as courtship displays. They dive with folded wings
and then rise with a few flaps, sometimes repeating this pattern up
to 20 times. Typically the female primarily incubates two eggs. Hatchlings
spend about 70 days in the nest before fledging, but remain dependent
on their parents for many months. During the first few weeks, the fledglings
are usually inconspicuous; they spend most of the time perched and receive
food from their parents. Over the next two months they slowly improve
their flying abilities before leaving their parents territories.
Subadult Golden Eagles lead a nomadic life before joining the breeding
population.
Description:
Golden Eagles are "booted eagles", their tarsi feathered
almost to the toes. They are not closely related to Bald Eagles, which
are "fish-eagles."
Golden Eagles are huge (33"38" long) with long broad
wings extending 6 1/2 to 7 1/2 feet across. The tail is fairly long
and square-tipped or slightly rounded. Adult birds are blackish-brown
overall. The golden-brown feathering on the crown and nape give the
Golden Eagle its name. The bill is gray with a black tip. Eyes, cere,
and feet are yellow. There is a bar of paler feathers on the upper wings,
and on the underwings the paler mottled primaries contrast with the
darker wing coverts. The undertail coverts, thighs and feathered tarsi
are usually paler as well. The tail shows two to four faint bands in
the adult plumage. Sexes are alike, although females are 40 percent
to 50 percent larger by weight. Juveniles have a white tail with a black terminal band. They show large
white patches at the base of the primaries on both the upper and lower
wing surfaces. In later subadult plumages the white wing patches are
greatly reduced and the base of the tail is mottled with brown. Recording credits: Copyright© 2002 Cornell Laboratory of Ornithology |