Wednesday, October 2, 2013

Eagle

From Wikipedia, the free encyclopedia

Golden Eagle
Eagle is a common name for some members of the bird family Accipitridae; it belongs to several genera that are not necessarily closely related to each other. Most of the more than sixty species of eagles occur in Eurasia and Africa.[1] Outside this area, just eleven species can be found – two species (the Bald Eagle and Golden Eagle) in the United States and Canada, nine species in Central America and South America, and three species in Australia.

Description

Bald Eagle
Eagles are large, powerfully built birds of prey, with a heavy head and beak. Even the smallest eagles, like the Booted Eagle (Aquila pennata) (which is comparable in size to a Common Buzzard (Buteo buteo) or Red-tailed Hawk (B. jamaicensis)), have relatively longer and more evenly broad wings, and more direct, faster flight – despite the reduced size of aerodynamic feathers. Most eagles are larger than any other raptors apart from some vultures. The smallest species of eagle is the South Nicobar Serpent Eagle (Spilornis klossi), at 450 g (1 lb) and 40 cm (16 in). The largest species are discussed below. Like all birds of prey, eagles have very large hooked beaks for tearing flesh from their prey, strong muscular legs, and powerful talons. The beak is typically heavier than that of most other birds of prey. Eagles' eyes are extremely powerful, having up to 3.6 times human acuity for the martial eagle, which enables them to spot potential prey from a very long distance.[2] This keen eyesight is primarily attributed to their extremely large pupils which ensure minimal diffraction (scattering) of the incoming light. The female of all species of eagle known is larger than the male.[3][4]
Eagles normally build their nests, called eyries, in tall trees or on high cliffs. Many species lay two eggs, but the older, larger chick frequently kills its younger sibling once it has hatched. The dominant chick tends to be the female, as they are bigger than the male. The parents take no action to stop the killing.[5][6]
Due to the size and power of many eagle species, they are ranked at the top of the food chain as apex predators in the avian world. The type of prey varies from genus to genus. The Haliaeetus and Ichthyophaga eagles prefer to capture fish, though the species in the former often capture various animals, especially other water birds, and are powerful kleptoparasites of other birds. The snake and serpent eagles of the genera Circaetus, Terathopius and Spilornis predominantly prey on the great diversity of snakes that are found in the tropics of Africa and Asia. The eagles of the genus Aquila are often the top birds of prey in open habitats, taking almost any medium-sized vertebrate they can catch. Where Aquila eagles are absent, other eagles, such as the buteonine Black-chested Buzzard-Eagle of South America, may assume the position of top raptorial predator in open areas. Many other eagles, including the species-rich Spizaetus genus, live predominantly in woodlands and forest. These eagles often target various arboreal or ground-dwelling mammals and birds, which are often unsuspectingly ambushed in such dense, knotty environments. Hunting techniques differ among the species and genera, with some individual eagles having engaged in quite varied techniques based their environment and prey at any given time. Most eagles grab prey without landing and take flight with it so the prey can be carried to a perch and torn apart.[7] The Bald Eagle is noted for having flown with the heaviest load verified to be carried by any flying bird, since one eagle flew with a 6.8 kg (15 lb) mule deer fawn.[8] However, a few eagles may target prey considerably heavier than themselves; such prey is too heavy to fly with and thus it is either eaten at the site of the kill or taken in pieces back to a perch or nest. Golden and Crowned Eagles have killed ungulates weighing up to 30 kg (66 lb) and a Martial Eagle even killed a 37 kg (82 lb) duiker, 7–8 times heavier than the predating eagle.[7][9] Authors on birds David Allen Sibley, Pete Dunne and Clay Sutton, described the behavioral difference between hunting eagles and other birds of prey thus (in this case the Bald and Golden Eagles as compared to other North American raptors):[10]
They have at least one singular characteristic. It has been observed that most birds of prey look back over their shoulders before striking prey (or shortly thereafter); predation is after all a two-edged sword. All hawks seem to have this habit, from the smallest kestrel to the largest Ferruginous – but not the Eagles.
Among the eagles are some of the largest birds of prey: only the condors and some of the Old World vultures are markedly larger. It is regularly debated which should be considered the largest species of eagle. They could be measured variously in total length, body mass or wingspan. Different lifestyle needs among various eagles result in variable measurements from species to species. For example, many forest-dwelling eagles, including the very large Harpy and Philippine Eagles, have relatively short wingspans, a feature necessary for being able to maneuver in quick, short bursts through dense forested habitats.[7] On the other hand, eagles in the genus Aquila are found almost strictly in open country, are superlative soarers, and have relatively long wings for their size.[7]
Here are lists of the top five eagles going on weight, length and, lastly, wingspan. Unless otherwise noted via reference, the figures listed are the median reported for each measurement in the guide Raptors of the World (Ferguson-Lees, et al.), in which only measurements that could be personally verified by the authors were listed.[7]
Rank Common Name Scientific Name Body Mass
1 Steller's Sea Eagle Haliaeetus pelagicus 6.7 kilograms (15 lb)
2 Philippine Eagle Pithecophaga jefferyi 6.35 kg (14.0 lb)
3 Harpy Eagle Harpia harpyja 5.95 kg (13.1 lb)
4 White-tailed Eagle Haliaeetus albicilla 4.8 kg (11 lb)[11]
5 Martial Eagle Polemaetus bellicosus 4.6 kg (10 lb)[11]
Rank Common Name Scientific Name Total Length
1 Philippine Eagle Pithecophaga jefferyi 100 cm (3 ft 3 in)[12]
2 Harpy Eagle Harpia harpyja 95.5 cm (3 ft 2 in)
3 Wedge-tailed Eagle Aquila audax 95.5 cm (3 ft 2 in)
4 Steller's Sea Eagle Haliaeetus pelagicus 95 cm (3 ft 1 in)
5 Crowned Eagle Stephanoaetus coronatus 87.5 cm (2 ft 10 in)
Rank Common Name Scientific Name Median Wingspan
1 White-tailed Eagle Haliaeetus albicilla 218.5 cm (7 ft 2 in)
2 Steller's Sea Eagle Haliaeetus pelagicus 212.5 cm (7 ft 0 in)
3 Wedge-tailed Eagle Aquila audax 210 cm (6 ft 11 in)[13][14]
4 Golden Eagle Aquila chrysaetos 207 cm (6 ft 9 in)
5 Martial Eagle Polemaetus bellicosus 206.5 cm (6 ft 9 in)

Species

Martial Eagle in Namibia
Philippine Eagle, Pithecophaga jefferyi in Southern Philippines
Wedge Tailed Eagle in Australia
Major new research into eagle taxonomy suggests that the important genera Aquila and Hieraaetus are not composed of nearest relatives, and it is likely that a reclassification of these genera will soon take place, with some species being moved to Lophaetus or Ictinaetus.[15]

Family

Main article: Accipitridae
Short-toed Snake Eagle in flight

Eagles in culture

Etymology

The modern English term for the bird is derived from Latin: aquila by way of French: aigle. The origin of aquila is unknown, but it is believed to possibly derive from either aquilus (meaning dark-colored, swarthy, or blackish) as a reference to the plumage of eagles or from aquilo (meaning north wind).
Old English used the term earn, related to Scandinavia's ørn / örn. It is similar to other Indo-European terms for "bird" or "eagle", including Greek: ὄρνις (ornís), Russian: орёл (orël), and Welsh: eryr. The Albanian word for eagle is shqiponjë, deriving from the root shqipe.
In Britain before 1678, eagle referred specifically to the Golden Eagle, with the other native species, the White-tailed Eagle, being known as erne. The modern name "Golden Eagle" for aquila chrysaetos was introduced by naturalist John Ray.[citation needed]

Religion

Garuda, the Vahana of Lord Vishnu, depicted with an eagle's beak and wings
The Moche people of ancient Peru worshiped the animal and often depicted eagles in their art.[17]
Despite modern and historic Native American practices of giving eagle feathers to non-indigenous people and also members of other tribes who have been deemed worthy, current United States eagle feather law stipulates that only individuals of certifiable Native American ancestry enrolled in a federally recognized tribe are legally authorized to obtain eagle feathers for religious or spiritual reasons.[18] In Canada, poaching of eagle feathers for the booming U.S. market has sometimes resulted in the arrests of First Nations person for the crime.[19]
In Hindu religion, Garuda is a lesser Hindu divinity, usually the mount (vahanam) of Vishnu. Garuda is depicted as having the golden body of a strong man with a white face, red wings, and an eagle's beak and with a crown on his head. This ancient deity was said to be massive, large enough to block out the sun.
The eagle is also the patron animal of Zeus. In particular, Zeus was said to have taken the form of an eagle in order to abduct Ganymede, and there are numerous artistic depictions of the Eagle Zeus bearing Ganymede aloft, from Classical times up to the present (see illustrations in the Ganymede (mythology) page.)
The Eagle is also the symbol of Libby, Montana which was recently named "The City of Eagles"[20][21]

As national symbols

See also: Eagles in heraldry
The coat of arms of Mexico – a golden eagle perched upon a cactus eating a snake
The coat of arms of Austria – a black eagle holding a hammer and a sickle, with a broken chain between its legs
Eagles have been used by many nations as a national symbol.
Historic uses:
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