An eagle may resemble a vulture in build and flight characteristics but has a fully feathered (often crested) head and strong feet equipped with great curved talons. A further difference is in foraging habits: eagles subsist mainly on live prey. They are too ponderousfor effective aerial pursuit but try to surprise and overwhelm their prey on the ground. Like owls, many decapitate their kills. Because of their strength, eagles have been a symbol of war and imperial power since Babylonian times.Eagles are monogamous. They mate for life and use the same nest each year. They tend to nest in inaccessible places, incubating a small clutch of eggs six to eight weeks. The young mature slowly, reaching adult plumage in the third or fourth year.
The harpy eagles, named after the foul, malign creatures (partwoman and part bird) of Greek mythology, are large, powerful,crested eagles of the jungles ofSouth America and the South Pacific. They nest in the tops of the tallest trees and hunt macaws, monkeys, and sloths. The great harpy eagle (Harpia harpyja; see photograph), which ranges from southern Mexico to Brazil, is about one metre (3.3 feet) long and bears a crest of dark feathers on its head. Its body is black above and white below except for a black chest band. It was becoming increasingly rare in the late 20th century, particularly in Mexico and Central America. The New Guinea harpy eagle (Harpyopsis novaeguineae) is about 75 cm (30 inches) long. It is gray-brown and has a long tail and a short but full crest. Very similar in appearance and habits is the monkey-eating eagle (Pithecophaga jefferyi; see ) of the Philippines. It is about 90 cm (35 inches) long, brown above and white below, with a crest of long narrow feathers. It is an endangered species.
The harrier eagles, six species of Circaetus (subfamily Circaetinae, serpent eagles), of Europe, Asia, and Africa, are about 60 cm (24 inches) long and have short unfeathered legs. They nest in the tops of trees and hunt snakes.
The hawk eagles (genera Spizastur, Spizaetus, Lophaetus, and Hieraaetus, subfamily Accipitrinae)are lightly built eagles that have fully feathered legs and large beaks and feet. They hunt all kinds of small animals. Spizaetus species (as the ornate hawk eagle, S. ornatus, of tropical America) have short wide wings, long rounded tails, and ornamented heads. Bonelli's eagle (Hieraetus fasciatus) of Mediterranean areas and parts of southern Asia, is about 60 cm (24 inches) long, dark above and light below, has a broad tailband, and usually shows a white patch on the back.
The martial eagle (Polemaetus bellicosus; see photograph) of Africa is heavily built, brown above with black throat and black-spotted white underparts. It has a short, barred tail and bright yellow eyes. It is large and strong enough to kill jackals and smallantelopes, but its usual food is gallinaceous birds and hyraxes.
The sea eagles (sometimes called fish, or fishing, eagles), species of Haliaeetus (see photograph), of which one of the best known is the bald eagle (q.v.), are very large eagles that live along rivers, biglakes, and tidewater throughout the world except South America. Some reach one metre (3.3 feet) long. All have exceptionally large high-arched beaks and bare lower legs. Undersurfaces of the toes are roughened for grasping slippery prey. These birds eat much carrion but sometimes kill. They snatch fish from the water surface and often rob their chief competitor, the osprey. Asian species include the gray-headed, or greater, fishing eagle (Ichthy ophaga ichthyaetus) and the lesser fishing eagle (I. naga).
The serpent eagles, or snake eagles, Spilornis (six species, subfamily Circaetinae), eat mostly snakes, including large poisonous ones. They occur in Asia. Other birds called serpent eagles, notably the long-tailed members of the genera Dryotriorchis (e.g. African serpent eagle) and Eutriorchis (e.g., the endangered Madagascar serpent eagle) occur in Africa.
Verreaux's eagle (Aquila verreauxi) is an uncommon bird of eastern and southern Africa. It is black with white rump and wing patches. It reaches about 80 centimetres (31 inches) in length, and it subsists mainly on hyraxes. See also bateleur; golden eagle.
Tuesday, 26 January 2010
19:22 Admin 1 comment