Technically, a hawk is a bird of prey belonging to the sub-family Accipitrinae. However, the term may be used more broadly to refer to any bird in the family Accipitridae, which includes the Accipitrinae, or, even more broadly, to nearly any bird of prey. Many birds that do not belong to the Accipitridae family have common names including hawk.
Hawks live all around the world. There are over 50 species of true hawk, most of which belong to the genus Accipiter. Most birds of this genus are known as goshawks or sparrowhawks. Hawks are skilled hunters that may feed during the night or day. Their prey includes smaller birds, mammals and reptiles, depending on the species of hawk.
Hawks are believed to be among the smartest birds, according to Dr Louis Lefebvre's methods of determining avian intelligence quotient (IQ), and they are renowned for their excellent vision. The hawk eye has about five times as many photoreceptors as that of humans, in addition to special nerves and muscles unknown in the eyes of other animals. They also have an indented fovea, at the back of the eyeball, which serves to magnify the center of the visual field. The typical hawk is believed to have 20/2 vision, as opposed to the 20/20 vision of an average human. This means that a hawk can see an object 20 feet (6 meters) away that a human could only see from a distance of two feet (0.6 meters).
Because of their excellent eyesight, intelligence, and natural predatory behavior, hawks are often used instead of eagles or falcons in the sport of falconry, in which the birds are used to catch small game. Many types of hawk in the United States are endangered as a result of human predation. People may shoot hawks to protect their livestock or simply as sport. Many hawk species around the world are protected against such treatment by law.