Eagles are large birds of prey which are members of the bird family. Eagles are differentiated from other birds of prey mainly by their larger size, more powerful build, and heavier head and bill. Even the smallest eagles, like the Booted Eagle. have relatively longer and more evenly broad wings, and more direct, faster flight. Most eagles are larger than any other raptors apart from the vultures. Like all birds of prey, eagles have very large powerful hooked beaks for tearing flesh from their prey, strong muscular legs, and powerful talons claws. They also have extremely keen eyesight 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 of the incoming light. Eagles 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.