Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagles are from Eurasia and Africa. Outside this area, just 14 species can be found—2 in North America, 9 in Central and South America, and 3 in Australia. Eagles are not a natural group but denote essentially any kind of bird of prey large enough to hunt sizeable (about 50 cm long or more overall) vertebrates. Description Eagles are large, powerfully-built birds of prey, with heavy heads and beaks. Even the smallest eagles, such as 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 and . The largest species are discussed below. Like all birds of prey, eagles have very large hooked beaks for ripping 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. It is estimated that the martial eagle, whose eyes are more than two times larger than the human eye, has a visual acuity up to 8 times that of humans. This acuity enables eagles to spot potential prey from a very long distance. This keen eyesight is primarily attributed to their extremely large pupils which ensure minimal diffraction (scattering) of the incoming light. The female of all known species of eagles is 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 parents take no action to stop the killing. It is said that eagles fly above clouds but this is not true. Eagles fly during storms and glide from the winds pressure. This saves the bird's energy. 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