The Strigiformes (Owls) are an order of birds of prey, comprising 200 extant species. Most are solitary, and nocturnal, with some exceptions (e.g. the Burrowing Owl). Owls mostly hunt small mammals, insects, and other birds, though a few species specialize in hunting fish. They are found in all regions of the earth except Antarctica, most of Greenland, and some remote islands. Though owls are typically solitary, the literary collective noun for a group of owls is a parliament.
The living owls are divided into two families, the typical owls, Strigidae, and the barn-owls, Tytonidae. Owls have large forward-facing eyes and ear-holes, a hawk-like beak, a flat face, and usually a conspicuous circle of feathers around each eye called a facial disc. Although owls have binocular vision, their large eyes are fixed in their sockets, as with other birds, and they must turn their entire head to change views.
Most owls are nocturnal, actively hunting for prey only under the cover of darkness. Several types of owl, however, are crepuscular, or active during the twilight hours of dawn and dusk; one example is the pygmy owl (Glaucidium). A few owls are also active during the day; examples are the burrowing owl (Speotyto cunicularia) and the short-eared owl (Asio flammeus). The time at which an owl hunts can be determined by the colour of its eyes.