The great hornbill (Buceros bicornis), also known as the concave-casqued hornbill, great Indian hornbill or great pied hornbill, is one of the larger members of the hornbill family. It occurs in the Indian subcontinent and Southeast Asia. It is predominantly frugivorous, but also preys on small mammals, reptiles and birds. It has been listed as Vulnerable on the IUCN Red List since 2018. It is known to have lived for nearly 50 years in captivity. Due to its large size and colour, it is important in many tribal cultures and rituals. The Government of Kerala declared it as the official Kerala state bird.
During the breeding season (January to April) great hornbills become very vocal. They make loud duets, beginning with a loud "kok" given about once a second by the male, to which the female joins in. The pair then calls in unison, turning into a rapid mixture of roars and barks. They prefer mature forests for nesting. Large, tall and old trees, particularly emergents that rise above the canopy, seem to be preferred for nesting. They form monogamous pair bonds and live in small groups of 2-40 individuals. Group courtship displays involving up to 20 birds have been observed.
The female hornbill builds a nest in the hollow of a large tree trunk, sealing the opening with a plaster made up mainly of feces. She remains imprisoned there, relying on the male to bring her food, until the chicks are half developed. During this period the female undergoes a complete moult. The young chicks have no feathers and appear very plump. The mother is fed by her mate through a slit in the seal. The clutch consists of one or two eggs, which she incubates for 38–40 days. The female voids feces through the nest slit, as do the chicks from the age of two weeks. Once the female emerges from the nest, the chicks seal it again.
The young birds have no trace of a casque. After the second year the front extremity separates from the culmen, and in the third year it becomes a transverse crescent with the two edges growing outwards and upwards, while the anterior widens to the width of the rear end. Full development takes five years.
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