Strigiformes

(vertebrate zoology) The order of birds containing the owls.

The owls, an order of nocturnal, worldwide predacious birds that are probably most closely related to the goatsuckers. The strigiforms are arranged in four families: Ogygoptyngidae (fossil), Protostrigidae (fossil), Tytonidae (barn owls; 11 species), and Strigidae (typical owls; 135 species). The bay owls (Phodilus), occurring in southern Asia and Africa, are somewhat intermediate between the Tytonidae and the Strigidae and are sometimes placed in a separate family; here they are treated as a subfamily, Phodilinae, of the Tytonidae.

Owls are small to medium in size, with soft plumage of somber colors. The large head has a facial disk that covers the feathered parabolic reflectors of the bird's acute directional hearing system. The eyes are large and capable of sight in very dim light, and the bill is strong and hooked. The wings are long and rounded, and the flight feathers are fringed for silent flight. The ulna has a unique bony arch on the shaft. Their strong legs are short to medium in length and terminate in strong feet. Owls are excellent fliers but walk poorly. Of the four toes on each foot, two point forward and two backward and bear strong claws. Prey is detected by acute night vision or by directional hearing; owls can locate and catch their prey in total darkness. Owls are generally nonmigratory and solitary, but some species live in small flocks. Courtship takes place at night with a male hooting to a female, which answers. A strong pair bond exists between the monogamous male and female, which usually build their nest in a tree cavity. Some species nest on the ground, on cliff ledges, or in abandoned crow or hawk nests. The clutch of up to seven eggs is incubated by both sexes, and after hatching, the young stay in the nest and are cared for by both parents. See also Aves.