Hornbill Bird

Hornbills  are a family of bird found in tropical and subtropical Africa. Asia and Melanesia. They are characterized by a long, down-curved bill which is frequently brightly colored and sometimes has a casque on the upper mandible. Both the common English and the scientific name of the family refer to the shape of the bill, "buceros" being "cow horn" in Greek. In addition, they possess a two-lobed kidney. Hornbills are the only birds in which the first two neck vertebrae  are fused together; this probably provides a more stable platform for carrying the bill.The family is omnivorous, feeding on fruit and small animals. They are monogamous breeders nesting in natural cavities in trees and sometimes cliffs. A number of species of hornbill are threatened with extinction, mostly insular species with small rangesHornbills show considerable variation in size as a family, ranging in size from the Black Dwarf Hornbill and 30 cm  to the Southern Ground Hornbill . Males are always bigger than the females, though the extent to which this is true varies dependent upon species. The extent of sexual dimorphism also varies with body parts, for example the difference in body mass between males and females is between 1-17%, but the variation is 8-30% for bill length and 1-21 in wing length.
The most distinctive feature of the hornbills is the heavy bill supported by powerful neck muscles as well as by the fused vertebrae.The large bill assists in fighting, preening, and constructing the nest, as well as catching prey. A feature unique to the hornbills is the casque a hollow structure that runs along the upper mandible. In some species it is barely perceptible and appears to serve no function beyond reinforcing the bill. In other species it is quite large, is reinforced with bone and has openings between the hollow centre allowing it to serve as a resonator for calls. In the Helmeted Hornbill the casque is not hollow but is filled with ivory and is used as a battering ram used in dramatic aerial jousts.Aerial casque-butting has also been reported in the Great Hornbill.
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