The singing apes

Print edition : January 30, 1999

The world of the hoolock gibbons in the Borajan reserve forest in Assam is dying, thanks to illegal tree-felling.


TWO whoops. I stop dead in my tracks and listen. Silence. Another whoop. Another silence. And suddenly, in a burst of pure tones, the ancient symphony begins. The forest stills, overwhelmed, transfixed. Each time, these moments of the old song are new to me. These moments of the life-song of the hoolock gibbon, echoing richly through the forest, scudding through the sunbeams, filling the heavens and stirring the earth. It is the call of the deep, dark rainforest.

Gibbons are small anthropoid apes that belong to the family Hylobatidae, the name deriving from "hylobates" or "dweller in the trees". Native to the rainforests of India, Bangladesh, Indochina and the Malay archipelago, they are considered to be the most agile, and the most musical, of all mammals. Gibbons are also the only higher primates that are monogamous. Often referred to as the lesser apes, there are nine recognised species of gibbons - all endangered.

The hoolock (Hylobates hoolock) is the Indian subcontinent's only ape. It inhabits the closed-canopy forests of northeastern India, Bangladesh, South Yunnan (China) and Myanmar. The Brahmaputra river forms the boundary of the hoolock's distribution in the north and west while the Salween river of Myanmar delimits its eastern distribution. Threatened by hunting and fragmentation and destruction of habitat for timber, agriculture and plantation, there were estimated to be fewer than 170,000 hoolock gibbons left in the wild 10 years ago. Later estimates put their numbers at fewer than 200 in Bangladesh, between 100 and 200 in Yunnan and some 6,000 in Assam. The population status elsewhere is mostly unknown, but the figures are likely to be very low with Myanmar possibly holding the largest remaining population.

Also known as the white-browed gibbon, the hoolock is a tree-living, fruit-eating and territorial primate. The life expectancy of the hoolock gibbon is not known (other gibbon species are known to live for more than 20 years). The male and the female pair monogamously for life and live in exclusive territories that they defend by loud calls and displays. The female normally gives birth to one offspring every two years. Each gibbon family is therefore a nuclear unit made up of the parents and two or three offspring. The sexually mature young disperse from their natal territories to establish new territories, find mates and begin new families. Young gibbons of both sexes and the adult male are black in colour. On attaining sexual maturity, usually at around seven years of age, the females change colour to golden brown.

I spent five months in the Borajan reserve, a 5 square-kilometre tropical semi-evergreen forest patch near Tinsukia in Assam, studying hoolock gibbons. Tea estates and cultivated areas surround the reserve and there is a forest village located inside it. Its small size and isolation from nearby forest areas and illegal tree felling make the continued survival of its wild denizens extremely precarious.

A female hoolock gibbon leaps across a gap in the forest canopy. Adapted to life in the high canopy, gibbons are rarely seen on the ground.-ABI TAMIM

IN Borajan, my day starts at 4 a.m. when I set off on my cycle for the reserve from Monkhooli village, my temporary home. It is still dark. And chilly. Once in the forest, I walk towards the tree where the gibbon family that I am going to follow that day is sleeping, find myself a convenient tree stump to sit on and wait for the gibbons to wake up with the first light of dawn. This time is enchanted. The hushed dew-dripping forest, the first tentative cheeps of the early birds, the quiet chatter of squirrels. The trees sway gently in the breeze, majestic and beautiful, defying the inevitability of their fate, for today. Tomorrow they may not be standing anymore. A barking deer calls out close, startling me. Then the jungle goes silent again. A silence replete with soft, subdued sounds, the sounds of dawn after darkness in the forest. It feels awesome to be part of the ancient awakening. Even to think seems like sacrilege.

Then the sky lights up and the spell is broken. I can hear the pig-tailed macaques before I see them. Suddenly, they are all over, jumping from their sleeping places, shaking the leafy Mesua (nahor) branches, each intent on making the maximum noise possible. The capped langurs climb quietly to the higher branches that face east, all the better to soak up the warming sunrays, their long, lustrous black tails hanging in abstract order. And the gibbons wake up too, stretch out their long arms to the side and shake off the dew in a glorious body shake.

The nearest fruiting fig tree is the gibbons' first destination this morning. Their simple stomachs have evolved to digest fleshy fruits and figs, sources of readily available energy. Their agility and strong arms have enabled them to exploit fruits even at the terminal ends of branches which a heavy-bodied animal cannot normally reach. Unfortunately for the gibbons at Borajan, there are not many trees left to choose from. Besides, it is a lean season and there are hardly any fruiting trees to be found. They have to make do with leaves, which are more difficult to digest and probably put them under tremendous stress. This shortage of their preferred food could severely weaken the animals, making them susceptible to predators and disease. In the long term, food stress insidiously manifests itself as low reproductive success - a dead end for the population.

A BOUT of feeding over, the gibbons begin moving towards one of their favourite basking trees. They move along the branches, swinging, springing and leaping effortlessly through the canopy - unrivalled masters of the forest heights. This peculiar arm-over-arm locomotion or "brachiation" is characteristic of gibbons. Sometimes, while on the ground or along the bigger tree branches, they can walk on two legs too. In fact, gibbons are the only anthropoid apes that can walk truly bipedally; the other anthropoid apes, namely, the chimpanzee, the gorilla and the orangutan, tend to walk on all fours. Dr. J.R.B. Alfred and Dr. J.P. Sati of the Zoological Survey of India, who studied gibbons in Meghalaya, describe this peculiar ambling gait, arms stretched out to the sides or held up for balance, as "quite like that of a drunken man".

Adapted to life in the high canopy, however, gibbons are rarely seen on the ground. In Borajan, though, they sometimes have no choice but to descend to the forest floor and dash nervously across the treeless stretches to reach a food tree. Driven to desperation.

The female is golden brown with the white of the eyebrows extending further.-ABI TAMIM

They find for themselves a sunny spot on a leafless fig tree and settle down to bask. They laze on their backs, all arms and legs, while the winter sun warms them - a thermoregulatory trick to compensate for the body heat lost during the cold night. The tiny infant I call Scrawny (for obvious reasons) is still asleep, face down on his mother's tummy! These will be his last worry-free days. A warm, reassuring mother's body to clutch on to, sleep all day and feed on demand. Life ahead will be tough.

Unlike in other primates living in groups, there is hardly any aggression among members of the gibbon family. They are remarkably gentle with one another. Where resources suffice for everyone, competition is unnecessary. (Studies of pigmy chimpanzees or bonobos in the more resource-rich equatorial rainforests of the Congo have found that they are more peaceful in their ways than their cousins, the savannah chimpanzees, for whom aggression and violence is part of the everyday scheme of things.)

In the distance, a family bursts into song. Another pair close by takes up the chorus. My study troop sits up and looks in the direction of the calls. Two more hoots and... they are in it too. Full-throated and joyous, the sound of gibbon song ringing through the forest is simply unforgettable.

Why do gibbons sing? Experts have put forward a few possible explanations, the most likely one being that they do so for vocal defence of territory from neighbouring groups. The song would often preclude the need for overt aggression where there is the risk of injury. The duet of the male and the female is also thought to be a device to strengthen the bond between the two. Gibbons accompany their singing with vigorous acrobatics in the canopy. The joy of watching them is worth all the leeches and the endless rain that I have to put up with.

They alternately eat, rest and move confidently along their canopy highways. For a strictly arboreal species like the hoolock gibbon, a gap in the canopy is like a roadblock. In that case they either find a detour or abandon use of that part of their home that has become inaccessible. Illegal felling of large trees in Borajan has created so many large holes in the canopy that the forest is full of roadblocks for the gibbons.

The male hoolock gibbon is black in colour and has prominent white eyebrows.-ABI TAMIM

I watch as Junior, the older offspring, prepares to jump across a five-metre gap that her parents have leapt across with some difficulty. She moves back, gathers momentum, and is about to leap, when her courage fails her, and she stops. She moves back and tries again. And again. Thirty-one times! Then, tired, afraid, she just gives up and huddles there alone. At times like this, everything that I am doing seems meaningless. What will I do with all the information that I have on them if they are not going to be around much longer? What will I do about that fear in her baby eyes? She is still just a toddler in human terms.

In Brazil, Dr. Irwin Bern-stein, an enterprising conservationist, hit upon the idea of providing "bridges" made of ropes or branches to help the arboreal Howler monkeys that he was studying cross roads in a similarly fragmented habitat. But how many of these bridges will we make? In Borajan, and in the scores of other places where we callously destroy the homes of these beautiful creatures to make ours?

I hear Ram and Montu, my young local assistants, tagging trees in another part of the forest this morning, whistling frantically to me. This is our mode of signalling to one another so that we do not disturb the animals by shouting. A few labourers from the nearby tea estate have found a python coiled up inside a tree hollow. It is a magnificent specimen. I come again later in the afternoon to photograph it. But I am too late. It looks like another python has gone into gravy.

The winter sun dips behind the trees. Dusk always comes early in the forest. The gibbons chew their last mouthfuls for the day and move quietly and rapidly to the tree on which they sleep. This is a strategy to throw any watching predators off their tracks for the time when they are asleep and most vulnerable to attack. I have to scramble along my established (and sometimes not-so-established) trails on the ground to keep up with them and mark their sleeping tree with a small bit of chalk. If I lose them, it might take up a lot of time to find them again tomorrow.

Among tropical mammals, gibbons are the "earliest to bed" although nobody has quite been able to say why this should be so. It could be that because they feed on fruits, they obtain their required quota of nutrition and energy within a much shorter time. It could also be a tactic for avoiding predators, most of which are nocturnal. Settling down to sleep before the predator starts on its prowl would lower the chances of their being spotted.

Hoolock gibbons are tailless and their arms are longer than their legs.-ABI TAMIM

The common predators of the hoolock are the leopard, the clouded leopard and the python. Borajan has too small an area to support larger carnivores such as leopards; the python, therefore, seems to be the only large predator of the hoolock gibbon here. Considering the rate at which they are hunted, the pythons probably have to be more anxious about saving their own lovely skins.

The apes find a conveniently thick branch on the tree, with a fork to rest against, and snuggle up for the night. The male and the female hug each other - a yin-yang of black and blonde. I hang around for some more time, packing my field notebook and binoculars while they look down at me soulfully. After the first few days of nervous vocalisations and wary looks, they are getting used to me traipsing behind (and below) them all day long. They probably wonder why on earth I should even want to do such a thing. Little Scrawny always finds this time perfect to wake up and squeal and try his best to crawl all over his mother's head!

Back at the Wildlife Institute in Dehra Dun, I shall analyse the data that I have collected, arrive at numbers, and look for identifiable patterns to substantiate the impressions I gathered in the field. Some of the figures are disturbing. The average home range size for gibbons in good forest is some 35 hectares. Here in Borajan, the gibbon families live in home ranges of less than seven hectares.

The home range of an animal is the minimum space that it needs to acquire for itself all the requisites for survival and reproduction - food, shelter and mates. When this space decreases, available resources also dwindle. With fewer food trees and safe sleeping sites, gibbons become extremely vulnerable to adverse episodes such as a poor fruit crop or a tropical storm, occurrences that they might normally have survived. A decrease in this space may also force them into encounters with neighbours, an event that is stressful even in the best of times. The familiar retreat paths available to them when threatened by predators are also cut off.

An even worse fate awaits the juveniles when they reach the age of dispersal. There simply will not be any new areas left to occupy and begin new families in. Pushed out of their natal homes, they are doomed to languish in the periphery of other established territories and eventually die. With no fresh recruitment, the population may be condemned to extinction.

A hoolock gibbon family, including an infant clinging to its mother. The members of the species are found to be monogamous.-S. SATHYAKUMAR

I visit two other reserves close to Borajan. I set out to do my assessments of the vegetation and find to my dismay that there really is not much use for my instruments here. Podumoni is an apology for a forest and Bherjan is only marginally better.

Both these areas (approximately 1 sq km each) are known to have had hoolock gibbons. Dr. Anwarrudin Choudhury, who has surveyed these areas, writes that the last gibbons in Podumoni died in the 1970s. Bherjan is left with one lone female after hunters killed her mate. She now apparently moves around with a group of pig-tailed macaques, calling out alone once in a while, her spirit broken and identity lost.

These places are surrounded by tea plantation and cultivation and subject to illegal felling of trees just as Borajan is. The gibbon populations here became locally extinct sooner because the effect of "diminishing resources" was intensified by their small sizes. For all practical purposes, the actual forest cover left in Borajan is only marginally higher. How much longer will its gibbons survive?

As time runs out for the gibbons, it is easy to give up the battle as lost. But there is still some hope. Within days of the Supreme Court's blanket ban in 1996 on timber felling in the northeastern States, the depressingly hollow sound of axe on wood became less frequent. Word got around that if the ban were lifted even for a few days, scores of trees would crash to the ground. But for some time at least, things were relatively quiet.

The majority of the human population around the reserve is employed as labourers in the adjacent tea plantations while the rest either cultivates small plots of land or hires itself out as daily wage labourers. The tea estate management gives out quotas of firewood from the plantations to their employees. Small amounts of firewood are nonetheless collected from the reserve for domestic use. Only a few people have made bigger business out of felling large trees for the timber, several of the species unfortunately being food trees of gibbons. Loppers who damage trees while collecting fodder for their milch cattle form another group. They seem to prefer climber figs and Dillenia (outenga) trees, again gibbon food plants. Although at a much slower pace, this dogged chipping away is nevertheless ruining the reserve and, for the gibbons, the future.

An infant hoolock gibbon that fell to the ground and suffered severe injuries.-KASHMIRA KAKATI

For the Forest Department, it is a Herculean task. In view of the fund crunches, it is an everyday struggle for the ill-equipped and under-staffed department just to hold the bigger national parks and sanctuaries together from the onslaught of illegal settlers, loggers and poachers. Small reserves such as Borajan seem to be nobody's babies. But the fact remains that a sizable proportion of the wild populations are found in such areas.

While the protection of these areas is crucial, the responsibility for this should not fall entirely on the Forest Department. Without the conscious support of the people living around the reserves, without a sense of guardianship among them, it would be difficult for the best-laid plans to be effective. And this is not as idealistic as it sounds. In the face of the worst atrocities, the Bishnois of Rajasthan have demonstrated the strength of their pledge to protect their wildlife. In Borajan, there is hope, with young boys like Montu and Ram. They were initially indifferent to the delights of the forest; the few months they spent following gibbons made them realise that they are in some way privileged to have such wonderful animals literally in their own backyards.

Today they come along with me on a night walk. The forest has fallen silent again. We see the sleeping capped langur silhouetted against the blue-grey night sky. We step softly, quietly. The night is not to be desecrated. Halfway down the trail, we catch a whiff - the unmistakable smell of a civet. We reach a huge strangler fig, the air all around ripe with the sweet smell of its fruits. A great-horned owl calls out - its deep, booming "boo-bo!" underlining the darkness before falling softly into it.

A scene inside the Borajan Reserve in Tinsukia. Illegal tree-felling is ruining the reserve and putting at risk the future of its wildlife.-ABI TAMIM

Incredibly, right below the strangler, my flashlight shines straight into the eyes of a leopard cat! Blinded by the light, it sits there blinking slowly, then walks away into the night in beautiful feline stealth. Ram and Montu watch wide-eyed and wonder-struck. For that moment, we are in a magic circle. They will not hurt the animals. Maybe they would have, but now they will not axe the trees they know the gibbons use.

That is what we need. Even if it is only a handful of aware young people who will grow up with a sense of responsibility and spread the message, be strong enough to tell off the ones who act thoughtlessly. Just a handful with the courage. And a handful to give them the guidance. There are a few of these beacons who work silently and tirelessly against all the odds. A few like Narayan C. Sarma, the Forest Range Officer of the Dibru-Saikhowa Wildlife Sanctuary. Extraordinarily dedicated to the wildlife in his care, fearless and always encouraging, he was an example worthy of emulation. Unfortunately, he died recently in a fatal attack by a rogue elephant. I remember how he cheered me up with his optimism on days that I felt like giving up all hope. Some day, the efforts of these brave workers will have to be rewarded, their prayers will have to be answered.

As I cycle back in the darkness, hundreds of flickering fireflies light up my path. Tonight, the stars have come down to earth. I know there is no one simple solution and it will not save all our forests, but at least it would be a beginning. Someone at least would have tried. Somewhere at least the gibbons would have lived as they were meant to, not just existed.

Kashmira Kakati studied the hoolock gibbons as part of her M.Sc (Wildlife Science) course at the Wildlife Institute of India, Dehra Dun.

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