Eastern Hoolock Gibbon (Hoolock leuconedys)


Gibbon is resting on tree branches at the forest
recstockfootage / Envato

The Eastern hoolock gibbon, scientifically known as Hoolock leuconedys, is a fascinating primate belonging to the gibbon family, Hylobatidae. It is one of three species of hoolock gibbon, distinguished by its unique characteristics and behaviors. This arboreal species is known for its distinctive vocalizations, complex social structures, and agile brachiation through the forest canopy.


A gibbon's curious eyes peek through
EvgeniiaFreeman / Envato

The Eastern hoolock gibbon exhibits striking physical features, including a characteristic white or pale eyebrow ridge, which distinguishes it from other gibbon species. Adult males and females display sexual dichromatism, with males showcasing a dark black coat, while females exhibit a contrasting light grey or buff coloration. These arboreal primates possess long arms, which are well-adapted for swinging and brachiating through the forest canopy. Their slender build and agile movements make them well-suited for life in the treetops.


Eastern Hoolock Gibbon
Edwin-Butter / Envato

The Eastern hoolock gibbon is primarily found in the eastern region of the Chindwin River, encompassing areas such as the Mahamyaing Wildlife Sanctuary. Its range extends across eastern India, including parts of Arunachal Pradesh and Assam, as well as into Myanmar and possibly into southern China. Notably, this species’ distribution is closely linked to the presence of suitable forest habitats, and its population density may be influenced by factors such as habitat fragmentation and human encroachment.

Habitat Preferences

The Eastern hoolock gibbon thrives in diverse forested habitats, including tropical and subtropical evergreen and semi-evergreen forests. These primates are highly dependent on the presence of a continuous forest canopy, which provides them with the necessary resources for foraging, nesting, and social interactions. However, habitat loss due to deforestation and human encroachment poses a significant threat to their survival, emphasizing the importance of conservation efforts to protect their preferred ecosystems.

By highlighting the unique characteristics, distribution, and habitat preferences of the Eastern hoolock gibbon, this species profile aims to increase awareness of the importance of conserving their natural habitats and fostering a deeper understanding of these remarkable primates.

Facts About Eastern hoolock gibbon

  1. The Eastern hoolock gibbon inhabits mountainous regions with elevations up to 8,860 feet (2,700 meters) (source: NE Primate Conservancy).
  2. This species is found in the extreme eastern corner of Assam and parts of Arunachal Pradesh, India, and Myanmar east of the Chindwin River (source: iNaturalist).
  3. The prime habitat of the Eastern hoolock gibbon in India is the lowland tropical forest in the Lower Dibang Valley district in the state of Arunachal Pradesh (source: BioOne).
  4. The Eastern hoolock gibbon occurs in Arunachal Pradesh and a small part of Assam (source: BioOne).
  5. Gibbons are sometimes called “long-armed apes” (source: NE Primate Conservancy).
  6. The Eastern hoolock gibbon is one of three species of hoolock gibbon (source: Wikipedia).
  7. Hoolock gibbons have been placed within their own genus, Hoolock, and split into two discrete species, the western hoolock gibbon and the Eastern hoolock gibbon (source: Wisconsin National Primate Research Center).
  8. The distribution of the Eastern hoolock gibbon in India is restricted to the eastern part of the state of Arunachal (source: PDF).
  9. The hoolock gibbons are native to eastern Bangladesh, Northeast India, Myanmar, and Southwest China (source: Wikipedia).
  10. The Eastern hoolock gibbon is known for its distinctive vocalizations, which include elaborate songs and loud calls (source: Personal Knowledge).

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