Great Hornbill(Buceros Bicornis)
They are also known as the concave-casqued hornbill, great Indian hornbill or great pied hornbill,The great hornbill is a large bird, 95–130 cm long, with a 152 cm wingspan and a weight of 2-4 kg. 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. 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. The back of the casque is reddish in females, while the underside of the front and back of the casque is black in males. The casque is hollow and serves no known purpose, although it is believed to be the result of sexual selection. Male hornbills have been known to 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. 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. They sometimes fly at great height over forests.
Habitat
Great hornbills are found in the forests of India, Bhutan, Nepal, Mainland Southeast Asia, Indonesian Island of Sumatra and North eastern region of India. The distribution of the species is fragmented over its range in the Indian subcontinent and Southeast Asia. In the subcontinent they are found in a few forest areas in the Western Ghats and in the forests along the Himalayas. They extend into Thailand, Burma, Malaya, and Sumatra. A small feral population is found in Singapore. Their habitat is dense old growth (unlogged) forests in hilly regions. They appear to be dependent on large stretches of forest, unlike many of the smaller hornbills. In Thailand the home range of males was found to be about 3.7 km2 during the breeding season and about 14.7 km2 during the non-breeding season.
Diet
Great hornbills are usually seen in small parties, with larger groups sometimes aggregating at fruit trees. A congregation of 150 to 200 birds has been recorded in southeastern Bhutan. In the wild, the great hornbill's diet consists mainly of fruit. Figs are particularly important as a food source. They obtain the water that they need entirely from their diet of fruits. They are important dispersers of many forest tree species. They will also eat small mammals, birds, small reptiles and insects. Lion-tailed macaques have been seen to forage alongside these hornbills. They forage along branches, moving along by hopping, looking for insects, nestling birds and small lizards, tearing up bark and examining them. Prey are caught, tossed in the air and swallowed. A rare squirrel, the Travancore flying squirrel has been eaten, and Indian scops owl, jungle owlet and Sri Lanka green pigeon have been taken as prey in the Western Ghats
Breeding
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.
Population
According to the IUCN Red List, they are classed as Vulnerable(VU). Their population trend is decreasing as there are threats of loss of habitat and hunting. The number of mature individuals is 13,000-27,000.
Threats
Forest loss likely has detrimental impacts on this species throughout its range, particularly as it shows a preference for forest areas with large trees that may be targeted by loggers. A deforestation analysis from 2000-2012 estimated the rate of forest loss within the species's range at 26% over three generations. Forests are lost to illegal logging and land conversion mainly for housing and agricultural developments, from small-scale agriculture to large-scale plantations. Because of its exceptionally large home range, the species requires extensive tracts of undisturbed forest and is unable to persist in areas where lowland forest has been reduced to small fragments. Proximity to human population is strongly avoided. In the species's stronghold in north-eastern India, only 5% of the landscape offers suitable habitat. Hunting poses a substantial threat to the species. Because of its predictable behaviour when regularly visiting the same feeding sites, it is easily targeted by local hunters. A survey in north-eastern India found that the species is mainly hunted for food as well as for its casque and tail feathers, which are used as adornments by local communities. Moreover, the species is highly prized for its fat, which is used for a variety of purposes, ranging from medical treatments to gun polish. The species is also captured for the pet trade, with chicks reported as being collected in south India and Thailand, and may also be taken as bycatch by hunters targeting Helmeted Hornbill.
Conservation
Conservation Actions Underway
CITES Appendix I. The species is captively bred in zoos. It occurs in several protected areas across its range. The ecology of the species has been studied since 1981 as part of long-running research at Khao Yai National Park in Thailand. Active management of nesting cavities has been used to augment breeding success in the wild. Hornbill Nest Adoption Programs have been implemented in Budo Sungai-Padi National Park in southern Thailand since 1994 and in forests adjoining Pakke Tiger Reserve in Arunachal Pradesh, northeast India since 2011. Urban donors are encouraged to 'adopt' wild hornbill nests and the funds raised are used to pay for nest guardians to monitor and protect the nest sites. An additional nest monitoring and protection program is underway in Kerala with the Kadar community and the forest department. Artificial nest boxes have been installed with some success at sites in Thailand and southern India.
Conservation Actions Proposed
Monitor populations across its range to determine the magnitude of declines and rates of range contraction. Campaign for the protection of remaining extensive tracts of lowland forest throughout its range. Develop a programme to reduce hunting of the species through raising awareness of the status of the species within communities that target the species. Develop the existing captive breeding population to support future reintroduction and supplementation efforts.