Post by bob on Oct 17, 2009 8:26:16 GMT -5
Adult Golden Eagles range considerably in size, though some are among the largest eagles of the genus Aquila. Most subspecies of Golden Eagle vary in the range from 65 to 100 cm (26–40 in) in length, wingspan can range from 150 to 240 cm (60–96 in), and weight is from 2.5 to 7 kg (5.5–15.5 lb). The smallest-bodied subspecies is A. c. japonica while A. c. daphanea is the largest on average.[1] However, wild specimens from Northwestern North America (A. c. canadensis) can exceed normal dimensions, as the largest recorded weighed 9 kg (20 lbs) and had a body length of 102 cm (40.1 in).[2] As with many Accipitriformes, females are considerably larger than males, in the case of the Golden Eagle they weigh one-quarter to one-third more than male birds.
The plumage colours range from black-brown to dark brown, with a striking golden-buff crown and nape, which give the bird its name.
The Golden Eagle is one of the large eagles in the genus Aquila, which are distributed almost worldwide. The latest research indicates it forms a worldwide superspecies with Verreaux's Eagle, Gurney's Eagle and the Wedge-tailed Eagle.[citation needed]
[edit] Subspecies and distribution
The type species is
* Aquila chrysaetos (Linnaeus, 1758) – Eurasia except Iberian peninsula, east to western Siberia.
Besides, there are five living subspecies of Golden Eagle that differ slightly in size and plumage. They can be found in different parts of the world:
* Aquila chrysaetos canadensis (Linnaeus, 1758) – North America.
* Aquila chrysaetos kamtschatica Severtzov, 1888 – Eastern Siberia, from the Altay to the Kamchatka Peninsula. Often included in A. c. canadensis.
* Aquila chrysaetos daphanea Severtzov, 1888 – Southern Kazakhstan east to Manchuria and south-west China, also northern India and Pakistan.
* Aquila chrysaetos homeryi Severtzov, 1888 – Iberian peninsula and North Africa, east to Turkey and Iran.
* Aquila chrysaetos japonica Severtzov, 1888 – Japan and Korea.
Golden eagle predominant prey is leporids (hares and rabbits) and sciurids (ground squirrels, prairie dogs & marmots), the two groups normally comprising 50-94% of the diet of nesting eagles. Additional mammals regularly taken include mice, martens, foxes, young deer. The secondary important prey group for eagles are other birds. Various gallinaceous birds (largely phasianids, ptarmigans and grouse) are the most significant avian prey. However, virtually any bird, from a jay to a swan, is potential prey. During winter months when prey is scarce, Golden Eagles scavenge on carrion to supplement their diet. Sometimes when no carrion is available golden eagles will hunt down large prey, such as goat-antelopes and caribou.[6] Reports have been made of mature adults killing wolves and other medium sized canine species.[citation needed] There is one confirmed report of a Golden Eagle snatching the cub of a Brown Bear, and several other unverified attacks.[7] Golden eagles are avian apex predators, meaning a healthy adult is not preyed upon. There are records of golden eagles killing and eating large raptors such as Eurasian Eagle Owls, Gyrfalcons, Goshawks and Buteo hawks, whether adults, nestlings or eggs. In Zion National Park, an adult eagle passing by a Peregrine Falcon nest was struck and killed by a swooping parent Peregrine.[8] Falcons, jaegers and Buteos like Rough-legged Hawks, which are normally competitors, have worked together to group-mob Golden Eagles that have passed their adjacent nesting areas.[9] More commonly, Golden Eagles kleptoparasitize, or steal prey, from other raptors. Despite being often smaller in size, they are capable of displacing large vultures, of both unrelated families, from carrion. However, the Bald Eagle and White-tailed Eagle can displace Golden Eagles in competition over food and vice versa. Golden Eagles have very good eyesight and can spot prey from a long distance. The Golden Eagle has a resolving power 8x more powerful than a human. The talons are used for killing and carrying the prey, the beak is used only for eating. They often have a division of labour while hunting, one bird driving the prey towards its waiting partner. On the other hand, the size difference between males and females allows more unpaired birds to live off the land, which is helpful to maintain a sufficiently large population for this large and slowly-maturing bird.
dult Golden Eagles range widely in size across their range. The largest races comprise the largest eagles of the genus Aquila. Length may vary from 66 to 100 cm (26-40 in), wingspan can range from 150 to 240 cm (59-95 in), and weight is from 2.5 to 7 kg (5.5-15.4 lb). As in all birds of prey, the females are generally slightly larger than the males. The largest golden eagle on record was a female caught in Spain, which measured 103 cm (41 in) in length and weighed in an excess of 9 kg (20 lb). She also held the record for the tallest Golden eagle, standing 66 cm (26 inches)[citation needed]. The largest North American Golden Eagle was captured for research in Grand Teton National Park in 2006, with a weight of 8.4 kg (18.5lb). She was caught by researchers Bryan Bedrosian and Tom Rogers working for Beringia South in Kelly, WY. She was determined to be healthy and released.
Berkut golden eagles from central asia were cited as averaging an incredible 6.5kg (making it the 3rd biggest of all) but so far no reliable data to support this, the wingspan, like most big eagles, avg 2.1m