owl, common name for nocturnal birds of prey found on all continents. Owls superficially resemble short-necked hawks, except that their eyes are directed forward and are surrounded by disks of radiating feathers. This peculiarity lends them an appearance of studious intelligence, and the owl has long been used as a symbol of wisdom. Although owls are able to see in daylight, their eyes are especially adapted to seeing in partial darkness, and most owls spend the day sleeping in caves, hollow trees, and other secluded places. Their plumage is so soft and fluffy that they are almost noiseless in flight. The order (Strigiformes) of owls is divided into two families; the barn owls (family Tytonidae), with heart-shaped faces, are one, and the typical owls (family Strigidae) compose the other. Owls feed on rodents, toads and frogs, insects, and small birds; like the hawks, they regurgitate pellets of indigestible matter. The elf and saw-whet owls of the SW United States and the pygmy owl of the Old World are only 6 in. (15 cm) long, while the eagle owl of Eurasia, the hawk owl of Australia, the great horned owl of North America ( Bubo virginianus ), and the snowy and great gray owls of the Arctic reach 2 ft (61 cm) with wingspreads of 4 to 5 ft (1.2 to 1.5 m). Many owls usurp the deserted nests of other birds, especially hawks; the burrowing owl of the New World lives in deserted prairie-dog burrows or digs its own. The barred owl has a familiar four-hoot call; the screech owl, misnamed for a similar European species, has a mournful descending cry. The long-eared owl is found in North America; the short-eared owl is ubiquitous. The tawny owl is common in England. Owls are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Strigiformes, families Tytonidae and Strigidae.
See J. A. Burton, ed., Owls of the World (1974), D. Morris, Owl (2009), and M. Taylor, Owls (2012).