Hornbills (Bucerotidae) are a family of bird found in tropical and sub-tropical Africa and Asia. They are characterized by a long, down-curved bill which is frequently brightly-coloured 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 (the axis and atlas) are fused together; this probably provides a more stable platform for carrying the bill.[1] 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 ranges.
Behaviour
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.

Diet
 
Female Great Hornbill feeding on figs. Fruit forms a large part of the diet of forest hornbillsHornbills are omnivorous birds, eating fruit, insects 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.[3] Forest living species of hornbills are considered to be important seed dispersers.[8]

In some instances hornbills defend a fixed territory.[1] 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.

Breeding
Hornbills generally form monogamous pairs, although some species engage in cooperative breeding. The female lays up to six white eggs in existing holes or crevices, either in trees or rocks. The cavities are usually natural, but some species may nest in the abandoned nests of woodpeckers and barbets. Nesting sites may be used in consecutive breeding seasons by the same pair. Before incubation, the females of all Bucerotinae—sometimes assisted by the male—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.[9] The sealing can be done in just a few hours, at most it takes a few days. Having sealed the nest it takes a further five days for the first egg to be laid. Clutch size varies from one or two eggs in the larger species to up to eight eggs for the smaller species. During the incubation period the female undergoes a complete and simultaneous moult. It has been suggested that the darkness of the cavity triggers a hormone involved in moulting.[10] Non-breeding females and males go through a sequential moult.[11] When the chicks and the female are too big to fit in the nest, the mother breaks out, then both parents feed the chicks.[1] In some species the mother rebuilds the wall, whereas in others the chicks themselves rebuild the wall unaided. The ground-hornbills are conventional cavity-nesters instead.[1]

Associations with other species
A number of hornbills have associations with other animal species. For example 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.[12] Other relationships are commensal, for example following monkeys or other animals and eating the insects flushed up by them.[13]

Hornbill can found in Koh Payam Ranong Thailand

**From Wikipedia**