Western hoolock gibbon

The only ape species present in India

Vijay Cavale

Western hoolock gibbon


The only ape species present in India

Population <5,000
90% decline in population

These tailless apes, found in the lush tropical forests of India, Bangladesh, and Myanmar, are distinguished by their long arms and abundant hair and are adapted to a life spent swinging from tree to tree, a behavior known as brachiation.

The males of the species are noted for their distinctive white eyebrow-like lines above their eyes, adding a striking visual element to their appearance. They weigh approximately 6.9 kg (15.2 pounds), showcasing the sexual dimorphism characteristic of the species. Females, on the other hand, exhibit a varied color palette in their fur, which can range from beige and brown to gray or yellow, and weigh slightly less, around 6 kg (13.2 pounds).

One of the most remarkable aspects of Western Hoolock gibbons is their vocalizations. They are known for their powerful and melodic calls that resonate through the forest. These sounds are not mere expressions of the gibbons’ presence; they serve a vital function in identifying and establishing territory. Males and females engage in beautifully coordinated duets, a harmonious blend of alternating high and low notes that quicken and escalate with each successive call.

However, the Western Hoolock gibbon faces significant threats that endanger its survival. The International Union for Conservation of Nature (IUCN) has projected a decline in their numbers over three generations, primarily due to hunting for food and medicine and habitat loss. These pressures have placed the Western Hoolock gibbon in a precarious position, highlighting the urgent need for concerted conservation efforts.

With their numbers estimated to have plummeted, the Western Hoolock gibbon’s situation is dire. Despite this, their ecological role as seed dispersers in the canopy of evergreen forests cannot be overstated. By consuming fruit and transporting seeds throughout the forest, they contribute to the regeneration and health of their ecosystem.


Population est.
Presence Uncertain

Did you know?

  • Are you having a bad day? At least you’re not threatened by a deadly combination of habitat loss by humans, forest destruction for tea cultivation, jumping (slash-and-burn cultivation), hunting for food and “medicine,” forest degradation, and capture for trade.
  • Since the 1980s, western hoolock gibbon numbers are estimated to have dropped from approx. 100,000 to less than 5,000 individuals. In 2009 it was considered to be one of the 25 most endangered primates, though it later made it out of the list.
  • Assessed as Endangered (IUCN 2017), this important seed is dispersed and lives in the canopy of evergreen forests. Pairs produce a loud, elaborate song, usually as a duet from the forest canopy.

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Terrestrial / Aquatic

Altricial / Precocial

Polygamous / Monogamous

Dimorphic (size) / Monomorphic

Active: Diurnal / Nocturnal

Social behavior: Solitary / Pack / Herd / Group

Diet: Carnivore / Herbivore / Omnivore / Piscivorous / Insectivore

Migratory: Yes / No

Domesticated: Yes / No

Dangerous: Yes / No