Most of us are familiar with charismatic mammals such as tigers, elephants and apes. And there are charismatic species amongst birds too: bustards, cranes, eagles. But in the Asian and African tropics are birds that gain charisma from their large size, spectacular appearance, and extraordinary breeding habits: the hornbills.
Malabar Pied Hornbill in flight
If you are a first-timer in a tropical forest in the Western Ghats of Karnataka, you may hear many unfamiliar sounds. An old man noisily clearing his throat, a repeated ‘kok’ as of a tree being hacked far away, a hen being strangled or taking flight in fright, or perhaps a shrill whistle that sounds like the familiar black kite of your city. It might take a while to track the sounds down, but when you do, you are in for a surprise: they may lead to a large, pied or monochromatic bird with a disproportionately large beak – a hornbill.
There are four hornbill species found in Karnataka: Great Hornbill (Buceros bicornis), Malabar Pied Hornbill (Anthracoceros coronatus), Malabar Grey Hornbill (Ocyceros griseus), or the Indian Grey Hornbill (O. birostris). The forests around Dandeli are one of the few regions where you can see all four species. Both the grey hornbills are endemic to India and the Malabar Pied Hornbill is endemic to India and Sri Lanka, while the Great Hornbill occurs across parts of India and Southeast Asia.
Great Hornbill (Buceros bicornis)
Malabar Pied Hornbill pair (Anthracoceros coronatus)
Malabar Grey Hornbill (Ocyceros griseus)
Indian Grey Hornbill (O. birostris). The presence of a small casque distinguishes this visually, from the Malabar Grey Hornbill.
The natural history and habits of hornbills are captivating: watching females incarcerated in tree cavity nests for 3 to 4 months, learning the variety of food the birds consume, or admiring their dexterity in picking choice ripe fruits or while hunting small animals. Witness any of this and you could be hooked on hornbills for a lifetime.
Hornbills are placed in two families: Bucerotidae (savannah and forest hornbills) and Bucorvidae (ground hornbills). They are most closely related to wood-hoopoes and hoopoes, which also lack pigments besides melanin, unlike other colourful birds. Of the 57 species of hornbills in the world, 25 occur in Africa. Of the 32 species of hornbills in the oriental region (south and southeast Asia), nine occur in India. Most are forest birds; only a single species, the Indian Grey Hornbill, occurs in wooded savannah.
One of the distinctive features of hornbills is the projecting casque mounted on the large curved beak, the shapes and colours of which give some species their names: Helmeted Hornbill, Red-knobbed Hornbill, and Rhinoceros Hornbill. The casque is hollow in all species
except the Helmeted Hornbill, whose is solid and is the main reason for them to be poached almost to extinction. The large beak and casque are used in various ways: to pick fruits ranging from small figs—a hornbill delicacy—to large nutmegs, to catch arthropods, lizards, snakes, even an occasional squirrel or bat, and to plaster doors onto their nest cavity openings. Malabar Pied and Great Hornbills may also clash their beaks in rare and spectacular aerial displays called casque-butting.
By eating fruits and dispersing seeds through droppings or regurgitation, hornbills aid in the regeneration of many mature forest trees. This service has earned them the title of ‘feathered foresters’. Hornbills are the only group, besides the large imperial pigeons, which consumes and disperses seeds of tree species such as Cinnamomum spp. (cinnamon, Lauraceae), Myristica spp. (nutmeg, Myristicaceae) and Canarium strictum (black damar, Burseraceae).
Malabar Pied Hornbill, feeding
Malabar Grey Hornbill (juvenile), feeding
Hornbills nest in cavities formed in old, tall trees where a branch breaks off and the wood rots. Unlike woodpeckers, hornbills cannot excavate their own nest. During nesting, the female incarcerates herself in the tree hollow for 3 to 4 months, and seals the entrance with her droppings, leaving only a slit through which the male delivers food to her and later to the chick.
The ecological and aesthetic values of hornbills are now widely appreciated. But, many species are highly threatened and endangered today due to human impacts. Illegal and unregulated logging of large trees, removal of trees with cavities as part of management, poaching, especially of nests, and the loss of native trees particularly large, old Ficus trees in the wider landscape, all pose significant threats to hornbill survival. Much of the hornbill forests that remain are fragmented. Trees in these fragments are vulnerable to desiccation and death from disturbances and climate change. Identifying and protecting nest and food trees wherever they are will go a long way to conserve hornbills.
Recent hornbill conservation efforts undertaken collectively by local people, researchers, forest staff, and conservationists in various parts of India suggest a way forward. These efforts now being carried out in a handful of places need to be expanded to many more areas if hornbills are to remain an awe-inspiring part of our lives.
Malabar Pied Hornbill (Anthracoceros coronatus)
An appeal to nature lovers, wildlife photographers and filmmakers
In recent years, there has been immense pressure on nesting hornbills, particularly the Great Hornbill, in many places, due to nature lovers, and wildlife photographers and film-makers. I would like to request those who wish to watch or photograph the species to avoid crowding around or near the nest trees. These hornbills are very shy and wary, and constant and close presence of people could make them abandon the nest, disrupt the feeding sessions, and thereby jeopardise the very survival and fitness of the chick. I am sure you all would agree that the lives of these hornbills and their successful breeding are more important than the images we make. A walk in the forest, a flight of hornbills overhead, or an encounter with a hornbill perched on a food tree can all be more exciting than a photograph of a nest. Although the image may need a little more hard work, it can be more rewarding both for the photographer and the hornbill.
Poonswad, P., Kemp, A. and Strange, M. 2013. Hornbills of the World
Kinnaird, M. 2008. The ecology and conservation of Asian Hornbills