Photography by Anand Mohan.
The pair soared in from just below the canopy, their size reminiscent of the ‘Roc’ from Sinbad’s voyage. Both birds were predominantly pied, had large tail feathers and bright yellow beaks. The beaks were big, sturdy and crowned with hard casques. “G. H. One male, one female,” whispered Khem, the field assistant accompanying us. The females have yellow irises, and the males red; a difference that takes a seasoned eye to notice from 40 feet (12 m.) below. “The nest is just ahead,” he added. As if sensing threat at this statement, the Great Hornbill pair began calling frantically. They flew around the canopy, their booming barks incessant, anxious for the safety of their nest. Great Hornbills, like all hornbills, nest in tree hollows. Their nesting ecology is one of the most interesting phenomena in nature. The pair selects a natural hollow in which to nest. The female then moves into the hollow and seals the entrance with her faecal material. She usually goes on to moult, lay the eggs (usually one or two) and incubate them. She stays confined within the nest until the eggs hatch. In smaller hornbills, the mother and chicks emerge together from the nest once the young are reasonably developed. For the Great Hornbill’s hollow however, even two is a crowd. The rather large mother usually needs to exit soon after the chick hatches. The female Great Hornbill helps her mate feed their young and defend their nest against threats.
Right now, the threat they sensed was us. We made haste in moving away. The parents followed us a short distance, still barking out warnings. They then flew back quietly, reassured. Calling loudly and continuously in alarm is a draining and expensive activity. This pair would need all the energy they had, to forage and feed a hungry beak.
Meanwhile, many such male hornbills were scouting this same forest; they gleaned treats from canopy and floor to take back to their nests. This might be an uncommon sight in most other places, but this wasn’t anything like most other places; we were in Pakke, one of the best forests to observe hornbills.
Located in East Kameng district of Arunachal Pradesh, the Pakke Tiger Reserve (also called Pakhui) is one of the lesser known reserves of India. It gets its name from the Pakke river that marks its south-eastern boundary. It is a tropical forest, nestled in the foothills of the eastern Himalaya. Contiguous with the Nameri Tiger Reserve, Pakke lies on the border of Assam and Arunachal Pradesh at the junction where the plains of Assam suddenly rise into the hills of Arunachal. Unique lives, both wild and human, inhabit this forest and our brief stay gave us a sneak peek into these lives. Our 30 days in Pakke were beautiful, singular and decisively educational.
Photograph by Kalyan Varma.
The routine – back, forth and back again
The purpose of our stay in Pakke was to volunteer with ongoing research to study and monitor hornbills. Aparajita Datta, a scientist at the Nature Conservation Foundation (NCF), has been studying these magnificent creatures for a decade and a half now. Amruta Rane, a researcher with NCF, is the project co-ordinator. The project involves monitoring of nests inside the park to determine nesting status and success and documenting the diet of hornbills at their nests. It also monitors phenology (fruiting and flowering cycles) of marked trees of many animal and mechanically-dispersed species. Three species of hornbills are found in the lower elevations of Pakke: Great Pied Buceros bicornis, Wreathed Aceros undulatus and Oriental Pied Anthracoceros albirostris. About 62 nests of the three species had been located and mapped, but many of these were gone. Currently, the team monitors about 35-40 nests every year. Our preliminary work was to visit each known nest site and confirm if it was active; meaning occupied, that year. Hornbills are secondary cavity nesters; they do not excavate nest hollows. Nests are usually cavities residual after the breaking of a branch, or are hollows excavated by smaller birds like woodpeckers. Hornbill pairs commence their search for a nest around January. Ideally, they find a hollow, lay their eggs and roam the forest with their young by September. This however, is the scenario without factoring in deforestation, and the competition it generates. Increasing loss of habitat, and therefore nest trees, has led to hornbills having to compete with individuals of the same and different species for nesting sites. Inter-specific competition at one site has been observed to the extent where a Wreathed Hornbill pair was ousted from a cavity they had occupied, by the much larger Great Hornbills. There are multiple records of hill mynas and monitor lizards occupying nest cavities. Nest hollows are even lost over time to the sinking of the floor due to rotting, flooding and closing down of the entrance caused by long gaps in occupancy. Each year, several pairs fail to breed successfully, either because they are unable to secure a nest or are forced to surrender their hollows to more daunting competitors. The ones that did nest successfully were the ones that we would have to monitor.
For first timers, the routine to get to these nests was a performance in itself. The Pakke river marked a natural divide, with our village on one bank and the protected forests on the other. A half finished (or half unfinished) bridge stood over the river. Every day, we’d walk over into Assam, cross the built-half of the bridge, wade the rest of the way, walk along the edge of Nameri, cross back into Pakke and then start hiking through the forest.
Walking in this forest was a thrill. We saw a crab-eating mongoose shoot across the grass and spotted a herd of four elephants feeding a few metres away. Birding in the Northeast was excitingly disorienting. The real challenge however, was to not get too sidetracked by the fantastic distractions en route. We had a nest to get to!
Photograph by Anand Mohan.
Of nest and nets
A hike down two nullahs, and we finally arrived at the nest site. It was located by a stream on the forest’s edge, habitat typical of an Oriental Pied Hornbill nest. The Oriental Pied Hornbill is the smallest of the three hornbill species in this area. That translates into a considerably smaller cavity size. The entrance had been sealed with faeces, leaving only a narrow, vertical slit. A careful minute’s stare and I could make out the shape of a beak peeking out through the opening. This opening was meant for passing in food brought by the male. In all hornbills, the male is responsible for procuring food for the female and the newly-hatched young for the entire period of their confinement. The male flies in with the food, perches near the entrance and feeds the mother and chicks through the slit. One way of studying their diet is to observe what the male brought to the nest from a clever vantage point. The fruits are usually brought whole, which makes identification easier.
Hornbills are mainly frugivorous, which is to say they eat mainly fruits. They typically swallow the fruits whole, and regurgitate the seeds. The mother and chicks, confined in the nest, spit the seeds out through the slit at the entrance. These seeds fall and collect over a very small area at the base of the tree. This behaviour has proved very ecologist-friendly since reliable data on diet can be obtained without having to sit still in a hideout for hours together. What goes in must come out, so the composition of seeds raining down from the cavity would tell us what the hornbills had been eating. Two square nets had been placed underneath each known nest. The nets had been positioned so as to catch the rain of regurgitated seeds. We only had to visit each nest routinely and record what seeds had fallen into the nets. This method saved us time and manpower, since data was automatically and continuously being collected for all the nests.
In addition to elucidating what hornbills eat in terms of non-fig fruits, this method could indicate how much of what they eat and what they disperse around nest sites. Most large fruits were already known or identified using existing keys. Many seeds in the Oriental Pied Hornbill’s net however, proved tricky. Being a smaller hornbill, its diet includes small fruits of lianas (woody vines) that are difficult to identify. We’d often find traces of animal remains like bone or crab shell as well. Most hornbills are omnivorous; possibly more so during the breeding season since many beaks to feed would logically make them less choosy.
Dietary information is crucial for conservation planning. Some key questions about hornbill biology can only be answered through long-term monitoring of diet and nests. Our work as volunteers was contributing to one such large data-set. Walking in Pakke and observing hornbill nests was an exciting routine. Watching two dozen hornbills fly in to their roosts made for a breathtaking finish.
Photograph by Kalyan Varma.
A ‘site’ to behold
Hornbills roost in colonies. The Oriental Pied prefers closed bamboo groves but the Great Pied and Wreathed Hornbills are known to roost in open trees in some of the riverine grasslands. Two such trees near the unfinished bridge, an Albizzia and a Bombax, were regular roosts for Wreathed Hornbills. The view from the bridge was a medley of visuals. Beyond the opposite bank lay the vast expanse of the Pakke and Nameri forests; strips full of the smoothest pebbles ran along the river; fields covered the area on our side of the bank and the river itself meandered on for as far as I could follow, reflecting every hue in the skyline. It was the perfect stage for an incredible show; and we had prime seats. Hornbills flew in from every direction, soared over our heads and into the tree. Once settled, they called continuously through sundown, ceasing a few minutes into complete darkness.
Apart from being a visual treat, roosts are a great tip-off about the current affairs in a hornbill population. The number of females at roost sites would shrink around theonset of the breeding season. The numbers would increase in mid-monsoon because many females and their new fledglings would start appearing.
The Wreathed Hornbill is a striking species showing high sexual dimorphism; sexes were therefore quite easy to tell apart in the field. Despite it being nesting season, we’d observe many pairs flying in to roost. They were probably the ones that did not find nests successfully that year or did not nest for some other reason. The Wreathed Hornbills would usually first assemble at the Albizzia, and later fly over to the Bombax on this bank to roost. On days when a pair of Great Hornbills occupied the Albizzia however, the Wreathed hornbill would avoid that tree and fly straight over to the Bombax.
Till even five to ten years ago, this same spot had many more trees being used as roosts by hornbills, with up to 0-100 birds using the site on both banks of the river. Great Hornbills used to roost in large numbers, but only a pair or single birds are seen now. In 2004, several roost trees were lost along the river bank as a result of a huge flood. Most remaining trees were lost to clearing of land for cultivation. Many roost trees lie outside Protected Areas and are at high risk of being felled or disturbed. These vulnerable roost sites need to be specially protected and incorporated along with nest trees into plans for hornbill conservation.
Photograph by Anand Mohan.
Hornbills are ecologically significant for one very important ecosystem service they offer: seed dispersal, especially for large-seeded fruits. Hornbills and Imperial Pigeons are some of the only birds with gapes large enough to swallow large-seeded fruit. Hornbills fly long distances while foraging and retain the seeds for long durations before regurgitating them, hence dispersing them far away from the parent tree. The seeds are spat out intact, are viable and have a good chance of germinating successfully. Hornbills are, in a way, responsible for shaping the forest’s growth and are called farmers of the forest. They’re large, colourful, unique and charismatic; features that appeal to us at a very fundamental level.
Locally called Paga, Poo and Garhe, hornbills are also held valuable by Nyishis, the local tribe. Nyishis have for generations, hunted hornbills for their meat, fat and casques. The meat is consumed and the fat is used in medicine. The upper beak and casques, especially those of the Great Hornbill, have high ornamental value in traditional headgear. The Nyishis admire the birds’ allure as well, but hornbills have traditionally served a more utilitarian than aesthetic purpose to them. Studies however, have shown a declining trend in hornbill populations, and have highlighted the need to reconcile conservation of hornbills with the sensibilities and traditions of he local community.
Reconciliation and conservation
An important part of preventing hunting is to offer alternatives. Gaon Burhas or local village heads now wear fibreglass replicas of casques in their headgear (See Sanctuary Vol. XXII No. 1, February 2002), thanks to an early initiative by the Wildlife Trust of India and Chuku Loma, a former DFO of Pakke. Over the decade, hunting has reduced considerably and the hunting that still goes on is done surreptitiously. This shows that in addition to the law, there is an emerging social norm discrediting hunting. But hunting is only one of the many threats hornbills face.
Extraction of truckloads of stone everyday from the river bed and bank could severely degrade their habitat. Trees, many of them nest trees like bhelu Tetrameles nudiflora, are felled. Being sensitive birds, disturbance from humans has often caused hornbills to abandon nests. Moreover, hornbills move over large areas, and many of their nest and roost sites are located outside Protected Areas, making community involvement in conservation imperative.
Photograph by Aparajita Datta.
The Ghora Aabhe (a council of village heads) together with NCF, have drawn up conservation plans where the communities will be made stake holders in hornbill protection. A scheme has been started wherein individuals are given monetary incentive for locating and reporting nests. These nests are then protected under the Hornbill Nest Adoption Programme. Donors, usually keen urban citizens, “adopt” a hornbill nest and take up the responsibility of paying a local candidate from one of the villages to regularly guard and monitor it. Furthermore, work is in progress to get an eco-tourism unit set up in Pakke, training locals to be guides and managers.
Despite many challenges, Pakke is a haven for hornbills in Arunachal Pradesh. This is a result of the cumulative efforts made by the Nyishis, the vision and commitment of various proactive forest officers which Pakke has been fortunate to have, especially Tana Tapi, countless unsung heroes among the forest staff (Sanctuary, Vol. XXX No. 2, April 2010), scientists and researchers from various local and national organisations.
Why do we need to save hornbills? There are several well-reasoned answers I brought back from our stay in Pakke; their role as seed dispersers, as flagships for conservation and as a great means of sensitising and getting local communities involved in the protection of wildlife. The most important reason however, is something very raw, very compelling and something that I cannot pen down in words. It’s in the rush I experienced each time we’d hear or sight these birds. It was in the amazement I could see light up the face of every passer-by who took a look through our binoculars. It’s moments like these where the pure magic of wilderness shines through. Its places like these that reinforce a simple fact that we sometimes question: that conservation is a battle worth fighting.
Photograph by Rajan Kr. Das.
by Anand Mohan, Sanctuary Asia, Vol XXXII No. 6, December 2012.