EAGLE, the name given to the larger diurnal birds of prey which are not vultures and which form the sub-family Aquilinae. They inhabit all regions of the world. Some seven or eight spe cies inhabit Europe, of which only one is now resident in Britain.
The golden eagle (Aquila chry saetus) inhabits the palaearctic and most of the nearctic regions. The plumage is dark brown, with the neck-feathers light tawny and the tail marbled with grey and lighter brown. It nests on cliffs, building a huge eyrie of sticks in which the female lays from two to four white eggs, mottled with red and purple. The same nest may be used year after year. The young are clad in white down. The Kirghiz Tartars use the gol den eagle to capture antelopes. Allied species include the imperial eagle (A. heliaca) of Asia and south-east Europe ; and A. pen nata of southern Europe, Africa and India, which is the smallest of all eagles.
A second British species was the erne, sea-eagle or white-tailed eagle (Haliaeetus albicalla), which inhabits the whole of the north ern part of the Old World, but has recently ceased to breed in Britain. The plumage is greyish-brown with a pale head, yellow beak and white tail. The nest resembles that of the golden eagle, but is more usually near water, for in addition to the hares, rab bits, grouse and other prey of A. chrysaetus, the erne eats fish and the refuse thrown up by the tide. Larger than either is H. pelagicus of eastern Asia, recognized by its white thighs and upper wing-coverts. Other species occur in south-east Europe, India, Malay, Australia, South Africa and Madagascar. All may be distinguished from the Aquila group by the bare, Sealy tarsi.
In America the golden eagle is found from Labrador and interior Alaska to central Mexico, breeding in suitable localities through out its range. The bald eagle (H. leucocephalus), the national emblem of the United States, is distributed from Maine to the coast of Alaska to northern Mexico, breeding throughout its range. Young birds in the first winter are streaked with brown and gray, much darker above. Later stages show heavy streaking of black and white on the under parts. Probably three years are required to attain adult plumage. Bald eagles are common in the lower Hudson valley when the river is frozen.
Local races of the bald eagle are H. 1. hypoleucus, a paler sub species found on Bering island, and the Alaskan H. 1. alascanus.
The monkey-eating eagle (Pithecophaga je ff eryi) is the largest of all eagles; it is related to the harpy (q.v.). It inhabits the Philippine Islands.
All eagles are remarkable for the power and stateliness of their flight, which is largely "soaring" in type, i.e., the wings are not flapped, but kept stretched out, and the bird appears to float through the air.
See C. W. R. Knight, The Golden Eagle (1927) ; F. H. Herrick, "Daily Life of the American Eagle," The Auk (1924) .