The term raptor refers to birds of prey, including eagles, hawks, buzzards, falcons & vultures. Less commonly, the term also includes owls. Sometimes "diurnal raptor" is used to distinguish eagles, hawks, etc. (which predominantly hunt during the daytime) and "nocturnal raptor" is used for owls (which predominantly hunt during the night). (It should be noted that both diurnal & nocturnal raptors may hunt at any time of day or night, depending on species & conditions). The word comes from the Latin word "rapere", meaning to seize & carry off, from which came "raptor" meaning plunderer, robber or ravisher.
One recent comprehensive book (Ferguson-Lees & Christie) recognises 313 separate species of diurnal raptor.
(In the following descriptions, I have loosely split the raptors into 4 categories. The first three categories are Owls, Vultures, Falcons. All other raptors [eagles, buzzards, true hawks, kites, etc] I have grouped together as hawks, this is purely for brevity in the text.)
With the exception of the vultures (which have evolved into scavengers) all of the raptors have adapted to using their feet to catch & kill their prey. Falcons tend to kill with the aid of speed, often by dropping from a great height (stooping) & striking the prey with their feet, either killing the prey outright, or, if not killed, the prey is dispatched by a twist of the beak to the spine. Many falcons have an elongated middle toe, which they wrap around the prey whilst still in flight. Hawks & owls tend to capture their prey in the feet, often on the ground, & kill the prey by crushing. Hawks feet have a ratchet-like mechanism to aid capturing & keeping their prey without too much exertion, allowing them to concentrate on any other possible predators. The hawk clenches her muscles, tightening the toes around the prey (gripping it with the talons), when the muscles are released, the toes & talons remain locked in place. Further clenching of the muscles tightens the grip on the prey (finally crushing it to death). The foot remains locked in this position, keeping a good hold on the prey, until the bird has fed itself, it is only then the muscles are released. occasionally, this can cause problems if the feet become locked on struggling prey & another predator decides to attack. There have also been sightings of sparrowhawks & marsh harriers drowning their prey.
Raptors are completely carnivorous and/or insectiverous (well nearly, the Burrowing Owl will eat fruit & seeds & the Palm Nut Vulture or Vulturine Fish Eagle (Gypohierax angolensis) is virtually vegetarian), obtaining all of their required nutrients from their prey. The nutrients which normally come from vegetable matter are often found in the stomachs of their prey. A lot of the water required for survival will also be extracted from the prey. Raptors will devour the prey entirely, regurgitating (casting) the indigestible matter in pellet form, once or twice a day. Raptors play an important part in population control in nature, preying on the weakest members of the prey population. This weeds out the sick, infirm, starving & often, genetically unsuitable members & thus helps keep a viable, healthy prey population.
All of the raptors have hook-tipped beaks, which are used for ripping the dead prey. Falcons have a notch on each side of the upper beak, forming a tooth-like projection (known as the nook) which, it is believed, aids breaking the spinal cord of the prey by biting. Lacking the nook of falcons, some hawks have a more pronounced hooked tip to the beak, probably for a similar reason. Vultures have developed a much larger, stronger beak well suited for tearing the hides of dead animals & cracking their bones.
Other features that raptors have in common are :