Context: Recently, a Primatologists have suggested rerouting a 1.65-km-long railway track that has divided an eastern Assam sanctuary dedicated to the western hoolock gibbon. 

Key report

• Their report in Science, a journal, follows that of the Wildlife Institute of India (WII) on designing an artificial canopy bridge to facilitate the movement of the hoolock gibbons across the broad-gauge line within the Hollongapar Gibbon Sanctuary.

• Housing about 125 hoolock gibbons, India’s only ape, the sanctuary covers an area of 21 sq. km.

Need

• Gibbon families on both sides of the railway track have been effectively isolated from each other, thereby compromising their population’s genetic variability and further endangering their already threatened survival in the sanctuary

• Like the other 19 gibbon species on earth, it is marked endangered due to habitat loss and habitat fragmentation.

About Hoolock Gibbons

• The hoolock gibbons are three primate species of genus Hoolock in the gibbon family, Hylobatidae.

• It is native to eastern Bangladesh, Northeast India, Myanmar, and Southwest China.

• The western hoolock gibbon is found in Assam, Mizoram, and Meghalaya in India.

• It is found where the canopy is contiguous, broad-leaved, wet evergreen and mixed evergreen forests, including dipterocarp forests and often in mountainous terrain.

Conservation Status

• IUCN Status: Western hoolock gibbon is classified as endangered.

• Schedule I of Wildlife Protection Act 1972

About the Hollongapar Sanctuary

• The Hollongapar Gibbon Sanctuary was formerly known as the Gibbon Wildlife Sanctuary or Hollongapar Reserved Forest.

• It is an isolated protected area of evergreen forest located in Assam.

• The sanctuary was officially constituted and renamed in 1997.

• The Hollongapar Gibbon Sanctuary contains India's only gibbons – the hoolock gibbons, and Northeastern India's only nocturnal primate – the Bengal slow loris.

• Flora: The Hollongapar Gibbon Sanctuary is classified as "Assam plains alluvial semi-evergreen forests" with some wet evergreen forest patches.The Bhogdoi River creates a waterlogged region dominated by semi-hydrophytic plants along the border of the sanctuary.

• Fauna: It houses about 125 hoolock gibbons. It also shelters six other primate species — the Assamese macaque, the Bengal slow loris, the capped langur, the northern pig-tailed macaque, the rhesus macaque, and the stump-tailed macaque.