Farmers of the forests

Great Pied Hornbill: Getting rare by the day. Photo: N. Shiva Kumar  

Bangalore to Beijing and Baghdad to Bangkok there will be no husband worth his weight in gold when compared to the hornbill. A bird blessed with immense patience and perseverance in the world of bird brain — a definition with which human beings tend to delight in describing other creatures. Taking this into cognisance, recently the Environment Ministry declined a proposal to set up a RADAR installation on a secluded Island in the Andamans — thus saving the remaining 300 wild Narcondam Hornbills from extinction.

Hornbills are a group of birds distinguished by very large bulky curved beaks. If that is not enough, most Hornbill species have an extra projection known as casque on the upper beak and the precise use of this outcrop has yet not been deciphered by scientists. The utility of such an enormous beak in these birds is intriguing because it is almost half the size of its body.

Watching hornbills in the Silent Valley and Periyar Sanctuary of Kerala and in the jungles of Digboi, Kaziranga and Namdapha national parks in the north east, I wondered whether the birds topple forward with their oversized beaks. However, I learnt that the big beak is not as heavy as it looks since it contains perforated spaces to make it lightweight. Perfectly built and suitably streamlined, the beak of the bird is designed to fly like an airbus with a “nozzle nose” in front. The big beak is, however, dexterously deployed to pluck ripened fruits and berries from tree-top canopies.

Scientists at the San Diego Safari Park, USA, explain that hornbills are the only birds in which the first two neck vertebrae (the axis and atlas) are fused together. This probably provides a stable platform for carrying big beaks with ample agility even while airborne.

While most hornbills inhabit thick jungles of the north-east and south-west India, Indian Grey Hornbill, the smallest, is sighted even in Allahabad, Chandigarh and Delhi due to availability of tree canopy. Basically arboreal, all hornbills are sighted in pairs as they tend to be life-long couples. As the birds grow older, their feathers turn black and yellow from grey. The beaks also obtain grey, yellow to orange and all hues in-between as they mature.

The most exceptional aspect of all hornbills is that they nest in naturally ‘prefabricated’ cavity of large trees that are refurbished with love and care. A peculiar characteristic of this bird during nesting is that the female stays inside the nest and is literally imprisoned. The male, assisted by the female from inside, seals the nest entrance leaving only a small opening for feeding the female. By this clever modus operandi, the eggs and hatchlings are protected from possible predators and vagaries of nature as well. The entire process takes about three to four months depending upon specific species.

Inside the nest, the female uses its own feathers to line up the nest bottom to cushion the delicate eggs and the chicks as they hatch. All the while, the male feeds the female and the fast growing chicks even as it itself becomes emaciated with the toil. The fresh growth of feathers on the female hornbill corresponds with maturity of the young chicks at which point the nest entrance is broken open and the mother escapes from its captive tree hollow. Now both parents feed the perpetually hungry chicks in the nest until they grow big enough to flutter away to freedom. As hornbills are omnivorous, they feed on fruits, occasionally crunchy insects, lizards; even rodents and small snakes are also relished.

Unfortunately, most of the 10 hornbill species in the subcontinent are now endangered due to fragmentation of forests, vanishing woodlands and mushrooming concrete jungles. These birds cannot live and procreate without the help of large trees. While the tree provides space to make a home in its wooden lair, the birds provide bird excreta rejected from the nest serving as manure for the tree. They are also excellent at dispersing seeds from the canopy to various locations propagating forest growth. A perfect example of interaction between two different organisms that is beneficial to both species, hence scientists the world over acknowledge that hornbills as the farmers of the forests.

In December last year, a Hornbill Festival was held in Nagaland to enhance the understanding of hornbills through tourism and a variety of cultural activities. The event used rock concerts, motor races, trekking, painting competitions, dance and drama to spread the message of nature conservation and to discourage tribal hunters who use hornbill beaks as decorative headgear for their rituals.

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Printable version | May 12, 2021 6:27:35 PM | https://www.thehindu.com/sci-tech/energy-and-environment/farmers-of-the-forests/article4348200.ece

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