Land where Hoolock Gibbon sings: Hollongapar Gibbon Sanctuary, Assam

It was summer of 2015 in Hollongapar Gibbon Sanctuary, Assam. I was a doctoral student at that time and was working towards the conservation of a medicinal forest tree species in the rain forests of Assam. For some study purpose we were traversing through dense forest trails and I was accompanied by my colleague and one forest guard. While I was lost in exploring the rich biodiversity, our forest guard suddenly stopped and pointed up in the branches of Hollong (Dipterocarpus macrocarpus) trees and slowly whispered to us ‘holou’.

A Hoolock Gibbon couple, Hollongapar Gibbon Sanctuary, Assam

In Assamese language Hoolock Gibbons are called as ‘Holou bandor’ (although they are not monkeys). Western Hoolock Gibbon also known as white-browed gibbons are the only apes of the Indian subcontinent. I looked up in the branches and was mesmerized to see a pair Hoolock Gibbon sitting high up on the tree branches. The couple was holding each other and caressing. The moisture laden wind was blowing through the swaying branches and our eyes met. I tried to get the moment clicked, but somehow the mystical ape slowly moved into the thicker canopy and could not be traced. I was overwhelmed by the very sight when I first saw Hoolock Gibbon in its natural habitat, so serene, so innocent.

Hoolock Gibbon (male) sitting on the branches

We followed the trail ahead, and the pitter patter of the raindrops on the broad leaves already started. It takes some time to reach the raindrops on the ground due to thick canopy. The forest floor was covered with high litter and biomass, not to mention abundant leeches too. Sometimes leeches help safeguard against illegal poaching and tree felling. Summers in these moist forests are usually hot, humid and sweaty alongwith mosquitoes and flies. Moreover, rainfall plays hide and seek althroughout the day. The upper canopy of the forest was dominated by the Hollong tree (Dipterocarpus macrocarpus), while the middle canopy was dominated by Nahar (Mesua ferrea). The lower canopy comprised of evergreen shrubs and herbs, bamboos and rattans. Hollong tree is one of the favourite trees of Hoolock Gibbon. I too love Hollong and Mesua (Nahor gos) trees due to their phenology, colour patterns, cultural, ethnic and economic importance.

Forest thickets in the Sanctuary
Understory of the forest

On the way, the elderly forest guard told us that the Hoolock Gibbons are mystical and shy but social creatures. They are monogamous and mate for life and form strong family bonds. The mated pairs stay together for several years and their family usually comprises of one adult male and one adult female and their offspring. He told that the adult male reaches out to adult female family and convinces her father to give away her daughter (just like social marriage). If the girl’s father is convinced then both male and female adults can start their own family otherwise, the couple elopes and leaves their family to start their own.

Hoolock Gibbon, Hollongapar Gibbon Sanctuary, Assam

Female often gives birth to a single offspring within three years and caresses the infant. Juveniles slowly develop thick white ring around their face and develop their art of singing. The mother and offsprings share close bond even when distance apart. After attaining adulthood, males frequently perform solos, singing, and females perform duets with adult males. Adult males have dark pelage while adult females have lighter pelage. Gibbons communicate with each other through songs. The morning or evening opera consists of a repeated series of hoots and hoops ‘whoo- whoo‘ can be heard several miles away. They have a unique way of singing notes which has varying significance for eg. to attract potential partners or to announce occupied territory.

Hoolock Gibbon on a tree bole

The Western Hoolock Gibbon is found in all the states of the north-east India but is restricted between south of the Brahmaputra river and east of the Dibang river. It is also found in east Bangladesh and north west Myanmar. Western Hoolock Gibbons are strictly arboreal and swing and can walk upright also. In Assam and different parts of Northeast India, it’s considered a bad omen if Hoolock Gibbon comes down on earth. Being omnivorous, they love to have fruits, leaves and insects. They help in pollination as well as dispersal of seeds, thus balance forest ecosystem. They prefer to spend their night sleeping on the tallest trees and descend from their sleeping sites during early morning hours,  to the valley below where they like to forage. After feeding, they sing for sometime.

The Western Hoolock Gibbon is listed as Endangered in the IUCN Redlist. Their population is gradually declining by almost 90% over the last 30 years, due to deforestation, habitat destruction, forest fragmentation, hunting for meat, poor availability of food and it is now considered to be one of the most endangered 25 primate species in the world. In India, its listed on Schedule 1 of the Indian (Wildlife) Protection Act 1972. In order to protect further decline in the population of the species, the Government of Assam upgraded the status of the Hoollongapar Reserve Forest in the Jorhat District of Assam to a Protected Area for the conservation of these lesser apes. Presently, there are many ongoing research and conservation activities being undertaken towards behavioural studies as well as conservation of the endangered lesser ape species in India. I wonder to what extent human beings can be selfish and greedy to hamper and ruin innocent lives and habitat of Hoolock Gibbons.

Hollongapar Gibbon Sanctuary, Jorhat, Assam

The sun was going down and we had to return back to our research centres. We followed the trail back, but there was no sign of Hoolock Gibbons, they might have climbed up high tree tops as night was approaching, although I could smell wild elephants nearby. I was hoping that for once I could see the Gibbon and boarded vehicle. And to my surprise I could listen the song of Hoolock Gibbon from a distance as if they were saying goodbye. I thanked the scintillating moment and left with a hope to meet again. Throughout, the journey, I was wondering, how Gibbons being an ape can be loyal to their partner and spend their entire life altogether. On the other hand, we humans fail to be committed and loyal and wear masks behind selfishness and greed. Are we truly almighty’s best creation??

We met again after 3 years in a different location in the remote forest fringe village of Kaziranga, but that’s a different story altogether. It was dark when I reached my destination and I slept with the everlasting memory of Hollongapar Gibbon Sanctuary and song of Hoolock Gibbons.

A forest trail in Hollongapar Gibbon Sanctuary, Jorhat, Assam

Thank you!!


Picture courtesy @internet

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© 2019 – 2021

Published by Dr. Chandrima Debi

Hi, I am Chandrima Debi. I am a Doctorate in Forestry and an independent researcher. Ever since childhood, I experienced deep-rooted connection with nature, forest and wildlife. I have written various research articles, case studies based on geology, forests, medicinal plants, biodiversity and conservation. Through this blog I share my experiences with nature and forests around us and aid towards the protection and conservation of biodiversity, wildlife and the values associated.

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