UKBirds

Golden Eagle

Aquila chrysaetos

The Golden Eagle (Aquila chrysaetos) 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. Despite being extirpated from some its former range or uncommon, the species is still fairly ubiquitous, being present in Eurasia, North America, and parts of Africa. The highest density of nesting Golden Eagles in the world lies in southern Alameda County, California. These birds are dark brown, with lighter golden-brown plumage on their heads and necks.

Golden Eagles use their agility and speed combined with extremely powerful talons to snatch up prey including rabbits, marmots, ground squirrels, and large mammals such as foxes, wild and domestic cats, mountain goats, ibex, and young deer. They will also eat carrion if prey is scarce, as well as reptiles. Birds, including large species up to the size of swans and cranes as well as ravens and Greater Black-backed Gulls have all been recorded as prey. They have even been known to attack and kill fully grown roe deer. The Eurasian subspecies is used to hunt and kill wolves in many native communities, where their status is regarded with great mystic reverence.

Golden Eagles maintain territories that may be as large as 155 square kilometres (60 sq mi). They are monogamous and may remain together for several years or possibly for life. Golden Eagles nest in high places including cliffs, trees, or human structures such as telephone poles. They build huge nests to which they may return for several breeding years. Females lay from one to four eggs, and both parents incubate them for 40 to 45 days. Typically, one or two young survive to fledge in about three months.

The Golden Eagle is a large, dark brown raptor with broad wings. Its size is variable: it ranges from 66 to 100 cm (26 to 39 in) in length and it has a typical wingspan of 1.8 to 2.34 m (5.9 to 7.7 ft). In the largest race (A. c. daphanea) males and females weigh 4.05 kg (8.9 lb) and 6.35 kg (14.0 lb). In the smallest subspecies (A. c. japonensis), the sexes weigh, respectively, 2.5 kg (5.5 lb) and 3.25 kg (7.2 lb). The maximum size of this species is a matter of some debate, although the normal upper weight limit for a large female is around 6.8 kg (15 lb) and large races are the heaviest representatives of the Aquila genus. Captive birds have been measured up to a wingspan of 2.81 m (9.2 ft) and a mass of 12.1 kg (27 lb) (the latter figure was for an eagle bred for the purposes of falconry). The sexes are similar in plumage but are considerably dimorphic in size, with females rather larger than males. Adults are primarily brown, with gold on the back of the crown and nape, and some grey on the wings and tail. Tarsal feathers range from white to dark brown. In addition, some birds have white "epaulettes" on the upper part of each scapular feather tract. The bill is dark at the tip, fading to a lighter horn color, with a yellow cere.

Juveniles have a darker, unfaded color, white patches in the remiges which may be divided by darker feathers, and a large amount of white on the tail with a black terminal band. Occasionally upper wing feathers of juveniles are also white, or birds lack white on the wing entirely. As the bird ages, the amount of white on wings and tail diminishes, and adult plumages is usually acquired by the fifth year.