OWL (AS. ale, 011G. au-ilu, via, hairela. Ger. Ellie, owl; probably onomatopoetic in origin J. Any of a numerous well defined group Of birds, the nocturnal birds of prey, constituting the Linn:can genus Strix. now the suborder Striges. Although they were formerly placed unhesitatingly in the order Raptures. of recent years there has been some tendency to separate them from the other birds of prey and place them near the nightjars. which they resemble to a re markable degree. In appearance the owls are distinguished from all other birds by the large size of their heads and their great eyes, which are directed forward and surrounded by more or less perfect disks of feathers radiating outward and nearly hiding the small hooked bill. The claws are sharp and curved, but, like the bill. less powerful than in the Faleonithe. The outer toe is generally reversible at pleasure, so that the toes can be opposed two and two. to give greater security of grasp. The wings, although generally long, are less adapted for rapid and sustained flight than those of the diurnal birds of prey. and the bony framework by which they are sup ported. and the muscles 'which move them, are less powerful. The owls in general take their prey. not by pursuit. but by surprise. to which there is a beautiful adaptation in the softness of their plumage and their consequently noiseless flight, the feathers even of the wings being downy, and not offering as firm a resisting surface to the air as in falcons. The soft and loose plumage adds much to the apparent size of the body, and also of the head; hut the head owes its really large size to cavities in the skull between its outer and inner 'tables' or bony layer:. which cavities communicate with the ear, and are sup posed to increase the sense of hearing. This sense is certainly very acute. and the ear is. in many of the species, very large, and has a con (.,aled yet external conch, which is found in few other birds. The feathers immediately surround ing the ear are often arranged in a kind of cone, serving a purpose like that of an ear-trumpet. owls can see well in twilight or moonlight, but poorly in the glare of the day. The eye itself is highly perfected. and the pupil remarkably contractile. The legs and feet oi owls are usual ly feathered to the toes, and in many species even to the claws.
The digestive organs much resemble those of the Falconidte, but there is no crop and the stomach is more muscular. The gullet is very wide throughout, and owls swallow their prey either entire or in very large morsels, the indi gestible parts gathering into little lumps or 'pel lets.' which are ejected after a time. These pel are to be found numerously where owls roost or nestle, and their examination reveals the bird's bill of fare. The largest species feed
on hares, fawns, and gallinaceous birds: others on small mammals, reptiles. birds, and large insects. Although they capture many small birds, mice form the principal element in their diet, and the owls are thus highly beneficial to agriculture, and should everywhere be protected and encour aged by farmers. Some owls also feed largely on fish ( see crabs, and the like, which they catch fur themselves.
The owl fancily (Strigicke) falls into two di visions—the Strigime and the Bubonimc. which are distinguished by differences in structure espe cially marked in the shoulder-girdle (consult Evans. Birds. New York, 1900). The former group is typified by the barn owl, the latter by our big barred or 'eat' owl. In size, owls vary greatly. The largest known species is the cir cumpolar gray owl (Syrnium or cotiaptcx nebu losum). from 27 to 2S inches long and more than 5 feet across the wings. The smallest known owl is the curious elf-owl ( Micrathene Whitneyi) of Ari zona. which is less than six inches long, and is further remarkable as having only 10 tail feath ers: all other owls, so far as known. have 12. All owls have a general likeness in colors—a mixture of browns, whites. and yellows. as be comes nocturnal marauders who wish to remain unobserved. especially during the day when they are at rest. The Arctic owl becomes pure white in winter. but is brown in the summer plumage. There is little difference between the sexes, and the young, called or 'howlets.' resemble the adults. Owls are found in all parts of the world and in all climates, and rather more than 200 species are known. Of these 17 occur in North America, besides a dozen more or less rec ognizable subspecies; and about 15 species are natives of Europe. Some have a very wide geo graphical range. especially those of northern re gions, and it is doubtful whether several species separately named in Europe and North America are really distinct, e.g. the barn-owl (q.v.). An other very widely distributed bird is the short eared owl (Asio accipitrinus), which occurs in nearly all parts of the world. It is fifteen inches long, variegated tawny and dark brown, with short ear-tufts of few feathers. It is common in the United States, is somewhat migratory, and is occasionally seen in small Clocks. A closely related species, rather more common generally, with long ear-tufts, is the American long-eared owl (Asio Wilsoniana). The hawk-owl, snowy owl, and great horned or eagle owl (qq.v.) are other handsome circumpolar species.