This is the largest family within the order of diurnal birds of prey or raptors (Falconiformes),occurring throughout the world except for Antarctica. The capture, holding and dismembering of prey requires specialized equipment, and all raptorspossess a hooked bill, the base of which is covered with a fleshy membrane called the cere, and strong curved claws, called talons, on their feet. The legs vary in thickness and length among species, depending on the type of prey taken. Eagles that prey on large mammals have strong, thick legs, while Sparrowhawks which feed on small birds have longer and more slender legs. The serpent-eagle has thicker scales on its legs which help to protect it from snake bites.
Members of this family have very sharp eyesight – about 8 times sharper than that of humans – that is used to spot prey from a long distance. Hearing is also acute. In most hawks and eagles, the females are larger than the males, although in some groups, they are less brightly coloured. Juveniles of most species differ quite markedly from adults in coloration and markings of plumage, and even the adult plumage of many species is variable (‘polymorphic’), all of which makes identification of raptors rather difficult. Flight characteristics and underwing markings are often the best clues to their identity. Some species have an obvious crest on the nape, while others will raise their head feathers like a crest when disturbed or excited. Nests are untidy-looking, often large, constructions of sticks built high in trees.
The long, broad wings of eagles, often with distinct “fingers” at the tips, are used to soar high into the sky, from where prey may be spotted over long distances. Hunting from perches inside forest or woodland, goshawks (or sparrowhawks) and buzzards, have shorter, more rounded wings that are more effective in short-range ambush attacks, during which the wings are quickly flapped, then held flat in a fast glide. All groups use thermals to gain height quickly, especially before making long distance movements, such as when migrating.