“As the eagle was killed by the arrow winged with his own feather, so the hand of the world is wounded by its own skill.” ~ Helen Keller
From the Wildlife and Nature Facebook page.
Eagles are large, powerfully built birds of prey, with a heavy head and beak. Even the smallest eagles, like the Booted Eagle or Red-tailed Hawk, have relatively longer and more evenly broad wings, and more direct, faster flight.
Most eagles are larger than any other raptors apart from some vultures. 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 most other birds of prey. They also have extremely keen eyesight (up to 3.6 times human acuity for the martial eagle) which enables them to spot potential prey from a very long distance. This keen eyesight is primarily contributed by their extremely large pupils which ensure minimal diffraction (scattering) of the incoming light. The female of all species of eagle known are larger than the male.
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.
Due to the size and power of many eagle species, they are ranked at the top of the food chain as apex predators amongst the avian world. The type of prey varies from genus to genus. Some eagles prefer to capture fish, though many eagles often capture various animals, especially other water birds, and are powerful kleptoparasites of other birds.
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 could be considered the largest species of eagle. They could be measured variously in total length, body mass or wingspan.
The 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. On the other hand, eagles in the genus Aquila are found almost strictly in open country, are superlative at soaring, and have relatively long wings for their size.
Read more at the Wikipedia article on Eagles.