DR Ambedkar IAS Academy


About Hoolock Gibbon

  • The forests of north-east India support the highest diversity of primates in India, including the only apes found in the country, the western hoolock gibbon (Hoolock hoolock) and the eastern hoolock gibbon (Hoolock leuconedys).
  • The western hoolock gibbon: Ithas a much wider range, as it is found in all the states of the north-east, restricted between the south of the Brahmaputra river and east of the Dibang river. Outside India, it is found in eastern Bangladesh and north-west Myanmar.
  • The eastern hoolock gibbon: It inhabits specific pockets of Arunachal Pradesh and Assam in India, and southern China and north-east Myanmar.
  • IUCN Status: The western hoolock is listed as Endangered in the IUCN Red List and the eastern hoolock is listed as Vulnerable,
  • Threat: Both species’ populations have been declining due to habitat destruction of various forms and hunting for meat.

Characteristics of the species:

  • With long and slender arms, hoolock gibbons are swift creatures, barely needing to step on the ground. They swing from tree to tree in a mode of locomotion known as Brachiation and can brachiate at speeds up to 55 km/hr., covering up to six meters in just one swing.
  • Males and females are of similar size, but can be differentiated easily by the colouration of their dense hair.
  • Males are black with a distinctive white brow, while females are copper-tan with dark brown hair on the sides of their face, and a clear central parting in the head hair. They form monogamous pairs that remain together for years, though mating outside the pair has been noticed in some individuals.
  • Hoolocks are famous for their emotive call that echoes across long distances in the forest, and is used by individuals to attract mates.
  • Females give birth to one offspring every 2-3 years, and it remains within the family group for 7-10 years.
  • Food system: Their diet comprises mainly of fruits, but they sometimes also consume leaves, shoots and flowers.

Population and its protection:

  • Populations of western hoolock gibbons have declined by almost 90% over the last 30 years, and it is now considered to be one of the most endangered 25 primate species in the world.
  • In India, it is listed on Schedule 1 of the Indian (Wildlife) Protection Act 1972.
  • Enhancing protection for the species, the Government of Assam upgraded the status of the Hoollongapar Reserve Forest in the Jorhat District of Assam to a Gibbon Wildlife Sanctuary in 1997, making this the first Protected Area ever named after a primate species.

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