Malabar Grey Hornbill’s Population on the Decline in Western Ghats

Its loud call is distinctive. A series of yelps that almost sound like manic laughter upon reaching a crescendo. It can be heard from a distance, making the Malabar grey hornbill an easy bird to spot in the tall wet forests of the Western Ghats. Its large range, within which high densities have been recorded, meant that the species was not considered at risk for extinction.

But things have taken a turn over the last couple of years with research indicating a decreasing trend in population of the Malabar grey hornbill (Ocyceros griseus). The IUCN Red List, which indicates global extinction risk status of species, notes, “There is sufficient evidence to infer that there is a rapid ongoing population reduction across the range at a rate of 30-49% over three generations. This is believed likely to continue unless the critical factors driving the decline are identified and reversed.”

The State of India’s Birds report 2020 too gave evidence to suspect that there is a considerable decline in the species’ population.

The report indicates a ‘long-term’ trend shows a 66.8% drop. Long-term trend is the change in the index of abundance (frequency of reporting) in 2014/15 relative to before 2000. A value of -15% indicates that there has been a 15% decline in frequency of reporting over that time period. The ‘current’ trend, meanwhile, shows a 3.3% reduction in numbers respectively – which indicates that there is an average annual decline of 3.3% in frequency of reporting over from 2014/15 to 2018/19, a 5 year time period.

Range-wide population trends generated from the citizen science portal, eBird, also tentatively place the rate of decline of the Malabar grey hornbill population in the 30-49% band over three generations. The IUCN SSC Hornbill Specialist Group, too, has raised concerns.

“The general population of the Malabar Grey Hornbill is on the decline. Some outliers may indicate otherwise. You might even find them in good numbers in certain areas and reserved forests, but overall, their densities are reducing,” says Anish Andheria, President, Wildlife Conservation Trust.

Nature’s gardener

The Malabar grey hornbill is endemic to the Western Ghats and associated hills of southern India and can be found from Nashik in Maharashtra to the southernmost hills. It prefers to inhabit evergreen and semi-evergreen moist forests in the tropics, but can also often be spotted in home gardens, timber plantations, and coffee and cardamom plantations that lie adjacent to their favoured habitats.

A cavity nester, the breeding season of the Malabar grey hornbill extends from February to May, with the female selecting mature trees that have significantly large trunks (height 36m +/-6m, girth 3m, +/-1m) to nest in. “The nest must also be at a greater height (17m, +/- 6m) to prevent predators from climbing in. A clutch of four eggs is laid. Incubation period is about 40 days, and fledgling period is 46 days. Fruits from the ficus trees, fishtail palms, etc. are typically eaten during breeding and non-breeding season, but the species is known to prey on snakes, lizards and small birds during breeding season and when they have to feed their chicks,” says Vinod Karnik, a conservationist, who has been conducting research on birds in the Western Ghats for over a decade.

The Malabar grey hornbill is an indicator species and has long been hailed by conservationists for the important role it plays in the forest ecosystem. It aids seed dispersal that helps the forest grow and thrive, thus indirectly supporting the local wildlife population and reducing human-animal conflict to a large extent.

“Certain seeds only germinate when they pass through the gut of a bird or a mammal. Since the Malabar grey hornbill is relatively big in size, it helps disperse larger seeds that smaller birds cannot consume. You may not notice an immediate impact in the forest, if their numbers reduce. In the long run, however, there will be an irreversible impact on the ecosystem since certain species of trees will not be able to survive without them,” says Andheria.

Multiple challenges

There are several threats to the Malabar grey hornbill’s population. Deforestation driven by agricultural conversion is thought to be one of the main reasons for the decline in their numbers. Another reason could be the non-availability of large trees that are suitable for nesting (the bird is incapable of excavating its own hollow and depends on natural hollows). “They need large good quality forests to thrive. You will find more hornbills in areas where historical damage is less and there is old forest growth. But while forest cover may have increased as per the Status of Forest Report 2021, the quality of forests has reduced. Dense forests, for example, have become less dense,” says Andheria.

Fragmentation of forest also affects the species. Potential threats could have also come from an undocumented shift in range for a competitor or predator, undetected disease affecting either the individuals of this species or limiting resources, or changed agricultural practice. “But more research is needed to confirm this,” says Karnik.

Last call

On January 10 2020, based on Bird Life International research, the International Union for Conservation of Nature revised the status of the Malabar grey Hornbill from “Least Concern”, where the species is evaluated with a low risk of extinction to “Vulnerable”, which means the species is threatened with global extinction.

But more needs to be done to ensure that the population does not decline even further. One step suggested is ensuring compliance with forest protection regulations within protected areas, to prevent loss of large trees with suitable cavities, or large trees that will develop large cavities. “We also need more data to understand the reasons for the reduction in their numbers and need to start thinking about the creation of artificial cavities and other ways to help give the species a helping hand to make a comeback,” says Karnik.

Conservation of this keystone species of the Western Ghats is essential and needs to be given the attention it deserves. “Failure to save the Malabar Grey Hornbill could have a cascading effect on the forest and wildlife that lives there in the long run,” says Karnik.

This story was first published in Mongabay India