Owls are birds from the order Strigiformes, which includes about 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing and feathers adapted for silent flight. Exceptions include the diurnal northern hawk-owl and the gregarious burrowing owl. Owls hunt mostly small mammals, insects, and other birds although a few species specialize in hunting fish. They are found in all regions of the Earth except Antarctica and some remote islands. Owls are divided into two families: the true owls, Strigidae; and the barn-owls, Tytonidae.