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Caeca wanting; oil-gland tufted. Sternum with two shallow notches, one on each side in the posterior margin; behind the ill-developed manubrium is a perforation as in Meropidae. Both carotids present as a rule, though there are exceptions. Spinal feather-tract not defined on the neck, which has no lateral bare tracts or apteria; no aftershaft; no down on bare parts of skin. Deep plantar tendons as in Coraciae.
An enormous bill, generally curved, and furnished in most genera with a casque upon the basal portion of the culmen. This casque varies in shape, and is generally hollow or cellular, but the anterior part is solid in Rhinoplax. Primaries 11. Tail-feathers 10. The under wing-coverts as a rule do not cover the basal part of the quills, and this may, as Mr. Ogilvie Grant has suggested, account for the extraordinary noise made by some of the larger forms when flying, the sound being produced by the air rushing between the quills. The eyelids are furnished with strong eye-lashes. The sexes are as a rule alike in plumage, but often differ in size, in the form of the casque, and in the coloration of the soft parts.
The Hornbills are a very well-marked family found nearly throughout the Ethiopian and Oriental regions and occurring also in the Papuan sub-region. They are especially remarkable for their nidification, the account of which was long regarded as a fable, but has now been confirmed by numerous observers. A hole in a tree is selected, and then the female, usually with the aid of the male, encloses herself and shuts up the orifice with the exception of a narrow vertical slit, by means of earth mixed with the birds’ own droppings. In some cases, as Aceros nepalensis and Lophoceros birostris, the droppings alone are used, and the process of enclosure is then performed by the female from within the nest. She is thus enclosed before she begins to lay, and apparently remains in the hole till the young, which are naked when they leave the egg, are fledged, being fed all the time by the male through the slit left in the enclosing partition, which just allows room for the bird’s bill to be pushed through. The eggs are white when laid, but generally become discoloured during incubation.
All Oriental forms belong to one subfamily. By Europeans in India, Hornbills are commonly but incorrectly, called Toucans. The true Toucans (Ramphastidae) are peculiar to South America and are allied to the Barbets.
Key to the Genera
Genus DICHOCEROS, Gloger, 1842
Size large. Bill very large, stout and much curved; casque large and broad, covering more than the basal half of the culmen, the sides flat and vertical behind, the top overhanging in front, the posterior edge broad, projecting over the head behind and rounded, the upper surface flat behind, concave in front, terminating anteriorly in two lateral points that are blunted in old birds. No conspicuous crest; feathers of head loose-textured; chin covered with feathers; tail slightly rounded at end. Sexes alike in plumage. The casque is small and pointed in front in the young and becomes gradually developed as in all Hornbills. A single species.
Coloration: Head all round as far back as ends of ear-coverts black. Neck all round fulvescent white; back, rump, scapulars, median and lesser wing-coverts, breast and under wing coverts black. Greater coverts and quills black, with the bases and ends white. Lower abdomen, upper and under tail-coverts white. Tail yellowish white, with a broad subterminal black band on each feather.
Bill and casque yellow, tinged with red at the tip and with orange in the middle. In the male the culmen in front of the casque, a triangular patch at each side of the anterior end of the casque, and the posterior portion of the casque are black, but not in the female, in which, however, the posterior portion of the casque is red. In both sexes the base of the mandible is black. Irides in male blood-red in female pearly white; eyelids black; orbital skin dark fleshy pink; legs and feet greenish plumbeous.
Size: Length about 52 inches; tail 15; wing 20; tarsus 2.9; bill from gape to point in a straight line 10.5. Females rather less, wing 18; bill from gape 9. Tenasserim birds are decidedly smaller than Himalayan.
Distribution: Along the Sahyadri or Western Ghats from the neighbourhood of Bombay to Cape Comorin; this bird is unknown elsewhere in the Indian peninsula, and is wanting in Ceylon, but is found throughout the Himalayas as far west as Kumaon, up to 5000 feet; and is generally distributed in Assam, Cachar, Tipperah, and other countries between Assam and Burma, throughout Burma, the Malay peninsula, and Sumatra.
Habits: Like the other large Indian and Burmese Hornbills this is a forest bird, and generally keeps to high trees; it appears never to descend to the ground. Wherever it is found, it makes its presence known by the great noise produced by its wings in flying, a sound that may be often heard a mile away. Its flight is an alternation of a series of flappings of the wings and of sailing along with the wings motionless, but the flapping predominates and the flight is less undulating than in many Hornbills. Sometimes this bird is found in pairs, more often in flocks of from five to twenty or more. The food consists mainly of fruit, but insects and lizards are also eaten, as Tickell has shown; the fruit or other food, as with many other Hornbills, is tossed in the air and allowed to fall into the bird’s throat. The nidification was observed first by Tickell, subsequently by Mr. B. Thompson, Major Bingham, and others, and is typical. The eggs, usually two or three in number, are laid about April in the Himalayas, but in February in Tenasserim, Kanara, and Travancore, and measure 2.62 by 1.88.
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