The forest's farmers
The Great Hornbill, Buceros bicornis, is an architect of the Western Ghats' forests. Primarily a fruit-eater, or frugivore, its diet consists of figs and the lipid-rich fruits from trees in the Lauraceae and Myristicaceae families. By consuming fruits from a wide variety of trees, these birds are seed dispersers. They obtain all their water from the fruit they eat. Studies have shown that Great Hornbills are responsible for dispersing the seeds of more than 40 different tree species.
Their large size and extensive range make their dispersal services particularly effective. A single Great Hornbill can cover a home range of up to 14.7 square kilometers in the non-breeding season. Research tracking the birds revealed they disperse 95 percent of the seeds from the fruits they consume away from the parent tree. The median dispersal distance is around 250-300 meters, but non-breeding birds have been recorded carrying seeds as far as 13 kilometers. This long-distance dispersal is important for connecting fragmented forest patches and ensuring genetic diversity among tree populations. Without them, the seeds of many large-seeded trees in families like Meliaceae and Myristicaceae would have no other dispersal agent.
A unique life cycle
The Great Hornbill's nesting behavior is a distinctive in the avian world. The birds are monogamous and form long-lasting pair bonds. For nesting, they require large, old-growth trees with natural cavities, often high above the forest canopy. Once a suitable cavity is found, the female seals herself inside using a plaster made of her own feces, food debris, and mud brought by the male. She leaves only a narrow vertical slit open.
Through this slit, the male feeds her and, later, the chicks for the entire nesting period, which can last for several months. A male might bring up to 13 meals a day. While sealed inside, the female undergoes a complete moult of her flight feathers. She incubates one or two eggs for 38-40 days. After the chicks are partially grown, the female breaks out of the nest, and the chicks then re-seal the entrance themselves. Both parents continue to feed the young birds through the slit until they are ready to fledge. This process depends entirely on the male's ability to find enough food and the availability of massive, mature trees, tying the species' survival directly to the health of the forest.