CHENNAI: The spectacular annual congregation of the Great Hornbills in their traditional roosting sites in Anamalai Hills, including the modified landscape of Valparai, has begun. It is this time of the year when hornbills exhibit their unique breeding and nesting habits, which includes a series of courtship rituals.
Males engage in mid-air acrobatics called casque-butting to weed out competition. The winner gets to woo the female by presenting delicious fruits, including figs to the female. Males also call out to their potential mates using a loud ‘kok’ sound.
There is a lot of beak rubbing in order to bond before the pair enters the breeding cycle starting December.
All these characteristics makes the Great Hornbill congregation during pre-breeding season a virtual treat for onlookers. Since Valparai roosting sites are outside protected area and easily accessible, amateur photographers and tourists tend to flock the area disturbing the birds.
Unlike other larger birds, Great Hornbills are secondary-cavity nesters, which means they nest in tree cavities made by other birds. They prefer large, tall trees that overlook valleys because they feel safe and secure. During the breeding season, the female hornbill enters the cavity and with the help of her mate, seals the entrance using their droppings and stays inside for months until the chick hatches out of the egg. She only leaves a small vertical slit open through which the male provides food for her and the chick inside the nest.
Typically, hornbills tend to use the same nest year after year. As per a recent study conducted by senior scientists from Nature Conservation Foundation (NCF) and published in Hornbill Natural History and Conservation, there are five nest trees found to be in use even after 27 years by Great Hornbills and one nest in use for 25 years by Malabar Grey Hornbill, which is another species often sighted in Anamalai Hills and a few other pockets of Western Ghats.
Divya Mudappa and T R Shankar Raman, senior scientists from NCF and co-author of the study titled “Nest monitoring and nesting status of sympatric hornbills in the Anamalai Hills, Western Ghats, India” with another research scholar Pooja Y Pawar, told TNIE: “Hornbills using the same nest trees for over two decades indicates the importance of individual nest trees. Many of these nest trees are located inside the private tea and coffee estates. The forest department and estate owners are taking steps to minimise the disturbance, but the growing interest among tourists and amateur photographers is causing hindrance to the conservation.”
India is home to nine species of hornbills, of which four—Great Hornbill, Malabar Pied Hornbill, Malabar Grey Hornbill and Indian Grey Hornbill—are found in the Western Ghats. The Anamalai-Parambikulam-Vazhachal region is particularly significant for Great Hornbill conservation.
Bhargava Teja, Deputy Director of the Pollachi division of Anamalai Tiger Reserve, told TNIE: “Our field staff regularly does night patrolling and doesn’t allow anyone near the roosting sites and nest trees. We have GPS locations of all such trees. Even if the nest trees are located inside the private estates, night safaris and hornbill tours are prohibited. The estate owners are also cooperating.”
However, sources said a private estate, located close to a prime roosting site, was operating hornbill sighting and photography tour for guests at a premium.
Experts say protecting hornbills, which are large-bodied wide-ranging birds, is crucial for the forest ecosystem. They are known as ‘farmers of the tropical forest’ due to the crucial role they play in seed dispersal.
Although there is no scientific Hornbill population census done so far, the population density assessments done in the past by NCF in the whole of Western Ghats show the Great Hornbill population was stable, while the numbers of Malabar Grey Hornbill is on the decline.
Shankar Raman told TNIE: “We don’t know why Malabar Grey Hornbill numbers are declining. Lot more research needs to be done. While one can attribute it to habitat loss and fragmentation, there would be other factors like climate and non-availability of fruit trees considering the decline is noticed even in Anamalai where there is such habitat loss or fragmentations for years. Because of the declining trend, the International Union for Conservation of Nature (IUCN) has put the Malabar Grey Hornbill in the red list as ‘vulnerable’ removing it from the category of Least Concern.”
Divya emphasised that it was important to protect the nest trees, especially in the plantation landscape since they are few in number and because of weather they are more susceptible. “If there are lots of people near the nest trees, the male hornbill will not come. They are very shy birds. Our studies show the amount of food delivered to the nest in a plantation vis-a-vis nest in a protected area, varies significantly. This would be because of disturbance. Also, in plantation landscapes, the male needs to travel a longer distance to get the food due to less availability. Further anthropogenic pressures may force the male to abandon the nest or would hamper the health of the female and growth of the chick inside the nest.”