Calao bicorne

Identification

The great hornbill is a large bird, 95–130 cm (37–51 in) long, with a 152 cm (60 in) wingspan and a weight of 2 to 4 kg (4.4 to 8.8 lb). The average weight of 7 males is 3 kg (6.6 lb) whereas that of 3 females is 2.59 kg (5.7 lb). It is the heaviest, but not the longest, Asian hornbill. With the separation of the ground hornbills into a separate family, Bucorvidae, the great hornbill reigns as the heaviest of all typical hornbills. Females are smaller than males and have bluish-white instead of red eyes, although the orbital skin is pinkish. Like other hornbills, they have prominent "eyelashes".<p>The most prominent feature of the hornbill is the bright yellow and black casque on top of its massive bill. The casque appears U-shaped when viewed from the front, and the top is concave, with two ridges along the sides that form points in the front, whence the Latin species epithet bicornis (two-horned). The back of the casque is reddish in females, while the underside of the front and back of the casque is black in males.<p>The casque is hollow and serves no known purpose, although it is thought to be the result of sexual selection. Male hornbills indulge in aerial casque butting, with birds striking each other in flight. The male spreads the preen gland secretion, which is yellow, onto the primary feathers and bill to give them the bright yellow colour. The commissure of the beak is black and has a serrated edge which becomes worn with age.<p>The wing beats are heavy, and the sound produced by birds in flight can be heard from a distance. This sound has been likened to the puffing of a steam locomotive starting up. The flight involves stiff flaps followed by glides with the fingers splayed and upcurled.<p>Like other members of the hornbill family, they have highly pneumatized bones, with hollow air cavities extending to the tips of the wing bones. This anatomical feature was noted by Richard Owen, who dissected a specimen that died at the Zoological Society of London in 1833.

Taxonomie

The great hornbill was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae. He placed it with the rhinoceros hornbill in the genus Buceros and coined the binomial name Buceros bicornis. Linnaeus specified the location as China. The genus name is from Latin becerus meaning "horned like an ox" which in turn is from the Ancient Greek boukerōs which combines bous meaning "ox" with kerōs meaning "horn". The specific bicornis is Latin and means "two-horned". The species is monotypic: no subspecies are recognised.<p>The species was formerly broken into subspecies cavatus, from the Western Ghats, and homrai, the nominate form from the sub-Himalayan forests. The subspecies from Sumatra was sometimes called cristatus. Variation across populations is mainly in size, Himalayan birds being larger than those from further south, and the species is now usually considered monotypic.

Nom scientifique

Buceros bicornis

Autorité

Linnaeus, 1758

Ordre

Bucerotiformes

Famille

Bucérotidés

Genre

Buceros

Répartition et habitat

The great hornbill is native to the forests of India, Bhutan, Nepal, mainland Southeast Asia and Sumatra. Its distribution is fragmented in the Western Ghats and in the foothills of the Himalayas. Deforestation has reduced its range in many parts of India such as in the Kolli hills where it was recorded in the 1860s. <p>It prefers dense old growth unlogged forests in hilly regions. It appears to be dependent on large stretches of rain forests.<p>In Thailand, the home range of males was found to be about 3.7 km (2.3 mi) during the breeding season and about 14.7 km (9.1 mi) during the non-breeding season. Molecular approaches to the study of its population diversity have been attempted.

Migration

Espèce sédentaire

Comportement

Mode de migration: Espèce sédentaire.

Conservation

Tendance de la population: en déclin.

Tendance de la population

en déclin