Falcon (bird), any bird of the genus Falco, type of the family Falconidae (q.v.), with twenty-seven species, universally distributed, except in the Pacific Islands. They are distinguished by the short, stout beak, very distinctly toothed, well-marked, generally yellow cere, long, pointed wings, and long, rounded tail. The outer toe is longer than the inner (except in the gyrfalcons), and the lower part of the leg is covered with scales arranged like network. These birds are noted for their high courage, keen vision, and swift flight, which when in pursuit of prey has been estimated at 150 miles an hour; and many species have been partially domesticated for hunting other birds and ground game. The Peregrine Falcon, formerly common, but now rare, in Britain, is bluish-grey, narrowly barred with black above, and reddish-white with transverse black bars below. The length of an adult male is about 15 inches; the female is somewhat larger, and has a more decidedly rufous tinge on the under surface. It is the female that is the falcon of sportsmen; the male is a tiercel, and a bird caught wild in full plumage is a haggard. These birds prey on partridges, grouse, and plover, and sometimes on marine birds. Some authorities attribute the grouse disease to the destruction of falcons, which, it is said, by destroying sickly birds aided in the perpetuation of a vigorous race. There are closely allied forms in the southern hemisphere, chiefly distinguished by darker plumage. The gyrfalcons (that is, the falcons that fly in gyres or circles), have a more northerly range, and are sometimes made a distinct genus (Hierofalco). The Norway gyrfalcon (F. gyrfalco), a rare British visitant, the Greenland (F. candicans), almost pure white, the Iceland (F. islandus), and the North American gyrfalcon (F. labradorus) have their habitats pretty accurately defined by their popular names. The Merlin (F. aesalon) and the Hobby (F. subbuteo) are British species, somewhat resembling, but smaller than, the Peregrine Falcon. The Lanner (F. lannarius) and the Saker (F. sacer) are natives of South-Eastern Europe and the adjacent parts of Asia and of North Africa.