The Hornbill

Hornbills (Bucerotidae) are a family of birds 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(a hollow structure that runs along the upper mandible). Hornbills are the only birds in which the first two neck vertebrae(the axis and atlas) are fused together; this probably provides a more stable platform for carrying the bill. Both the common English and the scientific name of the family refer to the shape of the bill.

The family is omnivorous, feeding on fruit and small animals. They cannot swallow food caught at the tip of the beak as their tongues are too short to manipulate it, so they toss it back to the throat with a jerk of the head. While both open country and forest species are omnivorous, species that specialise in feeding on fruit are generally found in forests while the more carnivorous species are found in open country. Forest living species of hornbills are considered to be important seed dispersers.

In some instances hornbills defend a fixed territory. Territoriality is related to diet; fruit sources are often patchily distributed and require long distance travel in order to find, thus species that specialise in fruit are less territorial. Hornbills show considerable variation in size as a family, ranging in size from the Black Dwarf Hornbill(Tockus hartlaubi), at 102 grams and 30 cm to the Southern Ground Hornbill(Bucorvus leadbeateri), at up to 6.2 kg and 1.2 m. Males are always bigger than the females, though the extent to which this is true varies dependent upon species. 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. Hornbills possess binocular vision, although unlike most birds with this type of vision the bill intrudes on their visual field.This allows them to see their own bill tip and aids in precision handling of food objects with their bill. The eyes are also protected by large eyelashes which act as a sunshade.

Hornbills are diurnal, generally travelling in pairs or small family groups. Larger flocks sometimes form in the non-breeding season. The largest assemblages of hornbills form at some roosting sites, where as many as 2400 individual birds may be found.

During breeding the female lays up to six white eggs in existing holes or crevices, either in trees or rocks.Before incubation, the females begin to close the entrance to the nest cavity with a wall made of mud, droppings and fruit pulp. When the female is ready to lay her eggs, the entrance is just large enough for it to enter the nest, and after she has done so, the remaining opening is also all but sealed shut. There is only one narrow aperture, big enough for the male to transfer food to the mother and eventually the chicks. The function of this behaviour is apparently related to protecting the nesting site from rival hornbills.A number of hornbills have associations with other animal species. For example, some species of hornbills in Africa have a mutualistic relationship with Dwarf Mongooses, in which they forage together and warn each other of nearby birds of prey and other predators.

Thanks to Wikipedia: http://en.wikipedia.org/wiki/Hornbill

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