Hornbill

Hornbill, the English name long generally given to all the birds of the family Bucerotidae of modern ornithologists, from the extraordinary horn-like excrescence (epithema) developed on the bill of most of the species, though to which of them it was first applied seems doubtful. Among classical authors Pliny had heard of such animals, and mentions them (Hist. Nat. lib. x. cap. lxx.) under the name of Tragopan; but he deemed their existence fabulous, comparing them with Pegasi and Gryphones—in the words of Holland, his translator (vol. i. p. 296)—“I thinke the same of the Tragopanades, which many men affirme to bee greater than the Ægle; having crooked hornes like a Ram on either side of the head, of the colour of yron, and the head onely red.” Yet this is but an exaggerated description of some of the species with which doubtless his informants had an imperfect acquaintance. Medieval writers found Pliny’s bird to be no fable, for specimens of the beak of one species or another seem occasionally to have been brought to Europe, where they were preserved in the cabinets of the curious, and thus Aldrovandus was able to describe pretty fairly and to figure (Ornithologia, lib. xii. cap. xx. tab. x. fig. 7) one of them under the name of “Rhinoceros Avis,” though the rest of the bird was wholly unknown to him. When the exploration of the East Indies had extended farther, more examples reached Europe, and the “Corvus Indicus cornutus” of Bontius became fully recognized by Willughby and Ray, under the title of the “Horned Indian Raven or Topau called the Rhinocerot Bird.” Since the time of those excellent ornithologists our knowledge of the hornbills has been steadily increasing, but up to the third quarter of the 19th century there was a great lack of precise information, and the publication of D. G. Elliot’s “Monograph of the Bucerotidae,” then supplied a great want. He divides the family into two sections, the Bucerotinae and the Bucorvinae. The former group contains most of the species, which are divided into many genera. Of these, the most remarkable is Rhinoplax, which seems properly to contain but one species, the Buceros vigil, B. scutatus or B. geleatus of authors, commonly known as the helmet-hornbill, a native of Sumatra and Borneo. This is easily distinguished by having the front of its nearly vertical and slightly convex epithema composed of a solid mass of horn1 instead of a thin coating of the light and cellular structure found in the others. So dense and hard is this portion of the “helmet” that Chinese and Malay artists carve figures on its surface, or cut it transversely into plates, which from their agreeable colouring, bright yellow with a scarlet rim, are worn as brooches or other ornaments. This bird, which is larger than a raven, is also remarkable for its long graduated tail, having the middle two feathers nearly twice the length of the rest. Nothing is known of its habits. Its head was figured by George Edwards in the 18th century, but little else had been seen of it until 1801, when John Latham described the plumage from a specimen in the British Museum, and the first figure of the whole bird, from an example in the Museum at Calcutta, was published by General Hardwicke in 1823 (Trans. Linn. Society, xiv. pl. 23). Yet more than twenty years elapsed before French naturalists became acquainted with it.  
  
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Great Indian Hornbill (B. bicornis). (After Tickell’s drawing in the Zoological Society’s Library.)  
  
In the Bucorvinae we have only the genus Bucorvus, or Bucorax as some call it, confined to Africa, and containing at least two and perhaps more species, distinguishable by their longer legs and shorter toes, the ground-hornbills of English writers, in contrast to the Bucerotinae which are chiefly arboreal in their habits, and when not flying move by short leaps or hops, while the members of this group walk and run with facility. From the days of James Bruce at least there are few African travellers who have not met with and in their narratives more or less fully described one or other of these birds, whose large size and fearless habits render them conspicuous objects.

As a whole the hornbills, of which more than 50 species have been described, form a very natural and in some respects an isolated group, placed by Huxley among his Coccygomorphae. It has been suggested that they have some affinity with the hoopoes (Upupidae), and this view is now generally accepted. Their supposed alliance to the toucans (Rhamphastidae) rests only on the apparent similarity presented by the enormous beak, and is contradicted by important structural characters. In many of their habits, so far as these are known, all hornbills seem to be much alike, and though the modification in the form of the beak, and the presence or absence of the extraordinary excrescence,2 whence their name is derived, causes great diversity of aspect among them, the possession of prominent eyelashes (not a common feature in birds) produces a uniformity of expression which makes it impossible to mistake any member of the family. Hornbills are social birds, keeping in companies, not to say flocks, and living chiefly on fruits and seeds; but the bigger species also capture and devour a large number of snakes, while the smaller are great destroyers of insects. The older writers say that they eat carrion, but further evidence to that effect is required before the statement can be believed. Almost every morsel of food that is picked up is tossed into the air, and then caught in the bill before it is swallowed. They breed in holes of trees, laying large white eggs, and when the hen begins to sit the cock plasters up the entrance with mud or clay, leaving only a small window through which she receives the food he brings her during her incarceration.

This remarkable habit, almost simultaneously noticed by Dr Mason in Burma, S. R. Tickell in India, and Livingstone in Africa, and since confirmed by other observers, especially A. R. Wallace3 in the Malay Archipelago, has been connected by A. D. Bartlett (Proc. Zool. Society, 1869, p. 142) with a peculiarity as remarkable, which he was the first to notice. This is the fact that hornbills at intervals of time, whether periodical or irregular is not yet known, cast the epithelial layer of their gizzard, that layer being formed by a secretion derived from the glands of the proventriculus or some other upper part of the alimentary canal. The epithelium is ejected in the form of a sack or bag, the mouth of which is closely folded, and is filled with the fruit that the bird has been eating. The announcement of a circumstance so extraordinary naturally caused some hesitation in its acceptance, but the essential truth of Bartlett’s observations was abundantly confirmed by Sir W. H. Flower and especially by Dr J. Murie. These castings form the hen bird’s food during her confinement.

(A. N.)

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1 Apparently correlated with this structure is the curious thickening of the “prosencephalic median septum” of the cranium as also of that which divides the “prosencephalic” from the “mesencephalic chamber,” noticed by Sir R. Owen (Cat. Osteol. Ser. Mus. Roy. Coll. Surg. England, i. 287); while the solid horny mass is further strengthened by a backing of bony props, directed forwards and meeting its base at right angles. This last singular arrangement is not perceptible in the skull of any other species examined by the present writer.

2 Buffon, as was his manner, enlarges on the cruel injustice done to these birds by Nature in encumbering them with this deformity, which he declares must hinder them from getting their food with ease. The only corroboration his perverted view receives is afforded by the observed fact that hornbills, in captivity at any rate, never have any fat about them.

3 In The Malay Archipelago (i. 213), Wallace describes a nestling hornbill (B. bicornis) which he obtained as “a most curious object, as large as a pigeon, but without a particle of plumage on any part of it. It was exceedingly plump and soft, and with a semi-transparent skin, so that it looked more like a bag of jelly, with head and feet stuck on, than like a real bird.”

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