Holou uthil tokou gosot (the gibbon climbed the palm tree)”: this first line of an old children’s rhyme in Assam, still recited in schools and homes, captures a lively image of the Western Hoolock gibbon swinging on a tokou palm (Livistona jenkinsiana), causing a commotion among birds and leaves. It is one of the earliest ways Assamese children encounter this charismatic primate; not as a creature of the wild, but as a familiar, playful neighbour. This neighbourly bond is most clearly seen in Barekuri village near Tinsukia, Assam, where local residents live alongside a small population of Western Hoolock gibbons. The residents protect the trees around their homes, refusing to cut them so that the gibbons can move freely. This village is thus becoming the model of community-led coexistence, showing how traditional reverence can translate into everyday conservation.
Known for its agility, song and strong family bonds, the Western Hoolock gibbon is found in the evergreen, semi-evergreen and tropical rainforests of Northeast India, particularly Assam, Arunachal Pradesh, Meghalaya, Mizoram, Manipur, Nagaland and Tripura. As India’s only non-human ape, the Western Hoolock gibbon represents an ancient evolutionary lineage. It also inhabits patches of forest in Bangladesh and Myanmar.
The gibbon occupies a vivid place in many poems, stories and oral traditions of Northeast India. The Karbi community of Assam, for instance, narrates the story of a man who was transformed into a gibbon and sent to the forest for his misdeeds; the tale reinforces a taboo against killing the species. The Idu Mishmi community of Arunachal Pradesh believes its goddess Awelimili gave birth to twins—the ancestor of humans and the ancestor of apes and monkeys. The gibbons are thus sacred. The states’ Digaru and Miju Mishmi communities hold similar beliefs.
The gibbon’s song is its signature trait. Each morning, pairs sing duets that can last several minutes and echo for several kilometres. In Rinsangre, West Garo Hills, villages believe hoolock gibbons call during festivals but fall silent at deaths, a faith that ensures the species is never harmed. In other states like Mizoram and Meghalaya, people believe the gibbons call more often during full moons and fall silent on new moons, a pattern woven into local weather lore.
The tailless primate is the second-largest gibbon species after the Siamang of Southeast Asia, measuring 60-90 cm in length and weighing 6-9 kg. Males and females are similar in size but strikingly different in colour. Males have a jet-black coat and white eyebrow streaks that frame a dark, expressive face. Females, in contrast, are grey-brown, with darker fur around the chest and neck. Both have white rings around the eyes and mouth, giving them a mask-like appearance. Infants are born pale, almost buff-coloured, and males darken as they mature, while females retain their lighter coats. They live in small family groups, typically a monogamous pair with their young, and defend territories through vocal displays. Their diet is primarily frugivorous, consisting of fruits, leaves, flowers and tender shoots.
Ecologically, the gibbon serves as a key indicator of forest health in the Northeast, as its survival depends on continuous canopy cover. Its long, muscular forelimbs are perfectly adapted for brachiation or the elegant, swinging locomotion that lets it move swiftly between branches without ever touching the ground. However, rapid development in the region, including the construction of roads, highways, railways, and their electrification with transmission lines, has increasingly fragmented forest canopies. Add to this the expansion of tea gardens, oil exploration and urban growth. These factors may pose a serious threat to gibbons’ long-term survival.
The Hollongapar Gibbon Sanctuary in Assam remains one of their last strongholds in India, a remnant of the once continuous lowland rainforest that stretched across the Brahmaputra valley.
This article was originally published as part of the December 16-31, 2025 print edition of Down To Earth