Bird Watching

GREAT INDIAN HORNBILLS IN PERIL

  GREAT INDIAN HORNBILLS IN PERIL
   DIPANJAN GHOSH
Introduction
In my recent trip to Arunachal Pradesh, I spent a day at Sessa Orchid Sanctuary to grow my acquaintance with Himalayan orchids in their natural habitat.  Adjoining to Sessa, there is Eaglenest Wildlife Sanctuary. Eaglenest and the surrounding forest stretching across the river Kameng is known for diverse avian fauna, i.e., actually a birder’s paradise. It is also one of the best places to watch hornbills in India. Eaglenest is the home of six out of nine hornbill species found in Indian subcontinent, viz., Indian grey hornbill, Oriental pied hornbill, Great Indian hornbill, Rufous-necked hornbill, Wreathed hornbill and the illusive Brown hornbill. Among them the great Indian hornbill is the majestic one. Its impressive size and colour have made it important in many tribal cultures and rituals in India from long ago.

 Eaglenest Wildlife Sanctuary is a prime birding site of Northeast India and a repository of some rare and threatened avian species (Photo: Dipanjan Ghosh).

King of the forest
The great Indian hornbill (Buceros bicornis) is the largest and heaviest of the hornbill species found in India. Great pied hornbill, concave-casqued hornbill or great hornbill, etc., are the alternative names of this large bird. In Nepali, they are called ‘Homrai’, meaning ‘king of the forest’. Great Indian hornbill inhabit mainly in evergreen and moist deciduous forests of South and Southeast Asia. In India, they are found in a few forest areas in the Western Ghats and in the forests along the Himalayas. Their distribution extends into Nepal, Myanmar, Thailand, Malaya, and Sumatra.
A mature great Indian hornbill is 100-130 cm long, with a 150 cm wingspan and a weight of 2-4 kg. The body has black and white colouration with a black face, back and under parts, a white neck, wing coverts and flight feathers. Females are smaller than males and have bluish-white eyes instead of red, although the orbital skin is pinkish. Great hornbills have prominent eyelashes. 

Brightly coloured horny casque on top of a very large bill is the hallmark of
             an adult Great Indian Hornbill (Photo: Dipanjan Ghosh).

The most prominent feature of the great hornbill is its very large bill, which bears a sizable, bright yellow and black coloured, concave, horny growth – the casque. Though its bill looks quite heavy, is actually very light; it is made up of thin-walled hollow cells. The casque serves no known purpose, except sexual attraction. The back of the casque is reddish in females, while the underside of the front and back of the casque is black in males.  Unlike others birds, hornbills have highly pneumatised bones, with hollow air cavities extending to the tips of the wing bones.
The great Indian hornbills are long-lived, living for nearly 35-50 years, or more in captivity. They are usually seen in small groups, larger groups occasionally aggregating at tall fruit trees in the vicinity. Great hornbills sometimes fly at great height over the forest canopies.  The flight involves stiff flaps followed by glides with the splayed and up curled wings.

It is said that the flapping sound of a great hornbill can be heard more than a half
            kilometre away (Photo: Rupak Ghosh Dastidar).

Feeding habit
Great hornbills are predominantly frugivorous, i.e., their diet consists mainly of fruits. Even they obtain the water that they need entirely from their diet of fruits. An interesting fact is that 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. 
Carbohydrate and lipid-rich fruits of Alseodaphne, Myristica, Persea, Vitex, etc., are eaten along with different types of figs. A mature bird is able to consume as many as 150 figs within one meal.Great hornbills fulfil their need of protein-rich food by means of eating small mammals like squirrel; birds like owl, jungle owlet; small reptiles and a huge number of insects. 
Breeding behaviour

These hollows on the tree trunk are the abandoned nests of great hornbill (Photo:
            Dipanjan Ghosh)
Large, tall and old trees, particularly emergent that rise above the canopy, seem to be preferred for nesting.  The great hornbills choose the highest branches with little foliage as roost site. They arrive punctually at sunset from long distances, following the same routes each day. Resting sites are used regularly, when feeling spent after the long flight, until late at dusk and later they sleep.
During the breeding season (from January to April), great hornbills form monogamous pair and live in small groups of 2-40 individuals. Once courtship and mating are over, the female finds a tree hollow and seals herself in with faeces and a plaster made up mainly of pellet of mud. The male gathers the pellets from the forest floor and then gives them to the female who stays inside the nest leaving a slit for a window big enough to receive food. The clutch consists of one or two eggs. The female remains imprisoned there for 6-8 weeks, where she incubates for 38-40 days relying on the male to bring her food, until the chicks are half developed. During this period the female undergoes a complete moult. She emerges after she has regrown fresh feather and her young are feathered. In the breeding season, males work hard. Some male hornbills are so exhausted after the nesting process that they may die.

Cultural and conservation status  
The great Indian hornbill is deemed as the state bird of two Indian states, such as Kerala and Arunachal Pradesh. Perhaps due to its impressive body colour, large size specially designed beak, great hornbill is considered important in many tribal cultures and rituals. Among the Sema Naga, Nishi, Zomi, Paite and some other tribes, a festival without hornbill feather in their head-dress is incomplete. Outside India, in Borneo also this is a common practice among aboriginals.
Unfortunately their population is declining rapidly in some areas of our country. Presently the great hornbill is evaluated as near threatened on the IUCN Red List of Threatened Species. It is listed in Appendix I of CITES also. Due to indiscriminate hunting by aboriginals for its various parts, the future of the great hornbill is in real peril. The beaks and head are used in charms, feathers are used during dance and the flesh is believed to be medicinal. Young birds are also considered a delicacy. Thus to entertain man’s illogical beliefs, those winged creatures has been gradually decreasing. Moreover, habitat loss in the form of forest clearance for agriculture, such as the slash and burn method of farming in Himalayas and Western Ghats, is also likely to have contributed to declines. Decline is also probably impacted by the pet trade to some extent.

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