1911 Encyclopædia Britannica/Owl

​OWL (O. Eng. Úle, Swed. Uggla, Ger. Eule—all allied to Lat. Ulula, and evidently of imitative origin), the general English name for every nocturnal bird of prey, of which group nearly two hundred species have been recognized. The owls form a very natural assemblage, and one about the limits of which no doubt has for a long while existed. They were formerly placed with the Accipitres or diurnal birds of prey, but are now known to belong to a different group of birds, and are placed as a suborder Striges of Coraciiform birds, their nearest allies being the goatsuckers. The subdivision of the group has always been a fruitful matter of discussion, owing to the great resemblance obtaining among all its members, and the existence of safe characters for its division has only lately been at all generally recognized. By the older naturalists, it is true, owls were divided, as was first done by F. Willughby, into two sections—one in which all the species exhibit tufts of feathers on the head, the so-called “ears” or “horns,” and the second in which the head is not tufted. The artificial and therefore untrustworthy nature of this distinction was shown by Isidore Geoffroy St-Hilaire (Ann. Sc. Naturelles, xxi. 194-203) in 1830. The later work of C. L. Nitzch on pterylography and of A. Milne-Edwards on osteology has led to a division of the family Strigidae into the sub-families Striginae, in which the unnotched sternum has its broad keel joined to the furcula, and Buboninae, in which the sternum is notched posteriorly, the clavicles do not always meet to form a furcula, nor meet the sternum. The Striginae contain the screech- or barn-owls (Strix) and the partly intermediate Heliodilus of Madagascar, whilst all the other genera are now placed with the Buboninae.

Among owls are found birds which vary in length from 5 in.—as Glaucidium cobanense, which is therefore much smaller than a skylark—to more than 2 ft., a size that is attained by many species. Their plumage, none of the feathers of which possesses an aftershaft, is of the softest kind, rendering their flight almost noiseless. But one of the most characteristic features of this whole group is the ruff, consisting of several rows of small and much curved feathers with stiff shafts—originating from a fold of the skin, which begins on each side of the base of the beak, runs above the eyes, and passing downwards round and behind the ears turns forward, and ends at the chin—and serving to support the longer feathers of the “disk” or space immediately around the eyes, which extend over it. A considerable number of species of owls, belonging to various genera, and natives of countries most widely separated, are remarkable for exhibiting two phases of coloration—one in which the prevalent browns have a more or less rusty-red tinge, and the other in which they incline to grey. Another characteristic of ​owls is the reversible property of their outer toes, which are when perching quite backwards. Many forms have the legs and toes thickly clothed to the very claws; others have the toes, and even the tarsi, bare, or only sparsely beset by bristles. Among the bare-legged owls those of the Indian Ketupa are conspicuous, and this feature is usually correlated with their fish-catching habits; but certainly other owls that are not known to catch fish present much the same character.

Among the multitude of owls there is only room here to make further mention of a few of the more interesting. First must be noticed the tawny owl—the Strix stridula of Linnaeus, the type, as has been above said, of the whole group, and especially of the Strigine section as here understood. This is the Syrnium aluco of some authors, the chat-huant of the French, the species whose tremulous hooting “tu-whit, to-who,” has been celebrated by Shakespeare, and, as well as the plaintive call, “keewick,” of the young after leaving the nest, will be familiar sounds to many readers, for the bird is very generally distributed throughout most parts of Europe, extending its range through Asia Minor to Palestine, and also to Barbary—but not belonging to the Ethiopian Region or to the eastern half of the Palaearctic. It is the largest of the species indigenous to Britain, and is strictly a woodland bird, only occasionally choosing any other place for its nest than a hollow tree. Its food consists almost entirely of small mammals, chiefly rodents; but, though on this account most deserving of protection from all classes, it is subject to the stupid persecution of the ignorant, and is rapidly declining in numbers.^[1] Its nearest allies in North America are the S. nebulosa, with some kindred forms, one of which, the S. occidentalis of California and Arizona, is figured above; but none of them seem to have the “merry note” that is uttered by the European species. Common to the most northerly forest-tracts of both continents (for, though a slight difference of coloration is observable between American examples and those from the Old World, it is impossible to consider it specific) is the much larger S. cinerea or S. lapponica, whose iron-grey plumage, delicately mottled with dark brown, and the concentric circles of its facial disks make it one of the most remarkable of the group. Then may be noticed the genus Bubo—containing several species which from their size are usually known as eagle-owls. Here the Nearctic and Palaearctic forms are sufficiently distinct—the latter, B. ignavus,^[2] the duc or grand duc of the French, ranging over the whole of Europe and Asia north of the Himalayas, while the former, B. virginianus, extends over the whole of North America. A contrast to the generally sombre colour of these birds is shown by the snowy owl, Nyctea scandiaca, a circumpolar species, and the only one of its genus, which disdains the shelter of forests and braves the most rigorous arctic climate, though compelled to migrate southward in winter when no sustenance is left for it. Its large size and white plumage, more or less mottled with black, distinguish this from every other owl. Then may be mentioned the birds commonly known in English as “horned” owls—the hibous of the French, belonging to the genus Asio. One, A. otus (the Otus vulgaris of some authors), inhabits woods, and, distinguished by its long tufts, usually borne erected, would seem to be common to both America and Europe—though experts profess their ability to distinguish between examples from each country. Another species, A. accipitrinus (the Otus brachyotus of many authors), has much shorter tufts on its head, and they are frequently carried depressed so as to escape observation. This is the “woodcock-owl” of English sportsmen, for, though a good many are bred in Great Britain, the majority arrive in autumn from Scandinavia, just about the time that the immigration of woodcocks occurs. This species frequents heaths, moors and the open country generally, to the exclusion of woods, and has an enormous geographical range, including not only all Europe, North Africa and northern Asia, but the whole of America—reaching also to the Falklands, the Galapagos and the Sandwich Islands—for the attempt to separate specifically examples from those localities only shows that they possess more or less well-defined local races. Commonly placed near Asio, but whether really akin to it cannot be stated, is the genus Scops, of which nearly forty species, coming from different parts of the world, have been described; but this number should probably be reduced by one half. The type of the genus S. giu, the petit duc of the French, is a well-known bird in the south of Europe, about as big as a thrush, with very delicately pencilled plumage, occasionally visiting Britain, emigrating in autumn across the Mediterranean, and ranging very far to the eastward. Farther southward, both in Asia and Africa, it is represented by other species of very similar size, and in the eastern part of North America by S. asio, of which there is a tolerably distinct western form, S. kennicotti, besides several local races. S. asio is one of the owls that especially exhibits the dimorphism of coloration above mentioned, and it was long before the true state of the case was understood. At first the two forms were thought to be distinct, and then for some time the belief obtained that the ruddy birds were the young of the greyer form which was called S. naevia; but now the “red owl” and the “mottled owl” of the older American ornithologists are known to be one species.^[3] One of the most remarkable of American owls is Speotyto cunicularia, the bird that in the northern part of the continent inhabits the burrows of the prairie dog, and in the southern those of the biscacha, where the latter occurs—making holes for itself, says Darwin, where that is not the case—rattlesnakes being often also joint tenants of the same abodes. The odd association of these animals, interesting as it is, cannot here be more than noticed, for a few words must be said, ere we leave the owls of this section, on the species which has associations of a very different kind—the bird of Pallas Athene, the emblem of the city to which science and art were so welcome. There can be no doubt, from the many representations on coins and sculptures, as to their subject being the Carine noctua of modern ornithologists, but those who know the grotesque actions and ludicrous expression of this veritable buffoon of birds can never ​cease to wonder at its having been seriously selected as the Fig. 2.—Strix flammea. symbol of learning, and can hardly divest themselves of a suspicion that the choice must have been made in the spirit of sarcasm. This little owl (for that is its only name—though it is not even the smallest that appears in England), the chevêche of the French, is spread throughout the greater part of Europe, but it is not a native of Britain. It has a congener in C. brama, a bird well known to all residents in India.

Finally, we have owls of the second section, those allied to the screech-owl, Strix flammea, the Effraie^[4] of the French. This, with its discordant scream, its snoring, and its hissing, is far too well known to need description, for it is one of the most widely-spread of birds, and is the owl that has the greatest geographical range, inhabiting almost every country in the world—Sweden and Norway, America north of lat. 45°, and New Zealand being the principal exceptions. It varies, however, not inconsiderably, both in size and intensity of colour, and several ornithologists have tried to found on these variations more than half-a-dozen distinct species. Some, if not most of them, seem, however, hardly worthy to be considered geographical races, for their differences do not always depend on locality. R. Bowdler Sharpe, with much labour and in great detail, has given his reasons (Cat. B. Brit. Museum, ii. 291-309; and Ornith. Miscellany, i. 269-298; ii. 1-21) for acknowledging four “subspecies” of S. flammea, as well as five other species. Of these last, S. tenebricosa is peculiar to Australia, while S. novae-hollandiae inhabits also New Guinea, and has a “subspecies,” S. castanops, found only in Tasmania; a third, S. candida, has a wide range from Fiji and northern Australia through the Philippines and Formosa to China, Burmah and India; a fourth, S. capensis, is peculiar to South Africa; while S. thomensis is said to be confined to the African island of St Thomas. To these may perhaps have to be added a species from New Britain, described by Count Salvadori as Strix aurantia, but it may possibly prove on further investigation not to be a strigine owl at all.  (A. N.)