The Northeast Frontier Railway (NFR) is planning to construct canopy bridges for Hoolock Gibbons to move across a railway track bifurcating Hollangapar Gibbon Sanctuary  in eastern Assam.

• The Mariani-Dibrugarh railway track (1.65 km long) which is set to  be doubled and electrified, divides the 2,098.62-hectare Hollongapar Gibbon Sanctuary in Assam into 2 halves.

About Canopy Bridge

• Aim: The decision to install canopy bridges is to facilitate easy movement of the gibbons across the track.
• Designed: The canopy bridges are designed by the WII in consultation with NFR.
• Design: The ends of the canopy bridges as well as the knots will be secured and clamped or tightened using appropriate and high-grade fastening materials and techniques. 
  • Safety mechanism: To save the species from accidentally falling off the bridges, safety nets will be installed below the main twin-rope bridge as a fail-safe mechanism.
• Natural design: The canopy rope bridges is supposed to mimic the natural design with  lianas and creepers being guided along them.

Enroll now for UPSC Online Course

Hollangapar Gibbon Sanctuary

• Location: In Jorhat district of Assam.
• Nature: The Hoollongapar Gibbon Sanctuary is a protected area of evergreen forest.
• Established: The sanctuary was officially established and renamed in 1997 and  is the only sanctuary in India named after a gibbon due to its distinction for containing the densest gibbon populations in India
• Unique Wildlife: 
  • The Sanctuary contains India’s only Ape’s  ie.  the Hoolock gibbons
  • It is home to northeastern India’s only nocturnal primate ie. the Bengal slow loris.
  • Highest Primates density: The Sanctuary is home to six other primate species, making it an area with the highest biodiversity of primate species of any Protected Area in the country.
• Flora:  The sanctuary has a rich diversity of flora at each layer in the canopy.
  • The upper canopy: It  is dominated by the Hollong tree, but other species found are Sam, Amari, Sopas, Bhelu, Udal and Hingori
  • The Middle canopy: Nahar dominates the middle canopy. 
  • The lower canopy: It  consists of evergreen shrubs and herbs.

Western Hoolock Gibbon

• About Hoolock Gibbon: The Hoolock Gibbons are three primate species of genus Hoolock in the gibbon family, Hylobatidae.
  • Western Hoolock Gibbon is the only Gibbon species found in India
• Native: To eastern Bangladesh, Northeast India, Myanmar, and Southwest China.
• IUCN Status: Endangered
• Habitat: They are found south of Brahmaputra and the North Bank areas and east of the Dibang Rivers.
  • Range in India: It  extends into the seven northeast states covering Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, and Tripura.
• Population: The Hoolock Gibbon Sanctuary supports  125 Individuals of the species, as of 2023
• Characteristic: They are diurnal and arboreal in nature.
• Threats: 
  • Fragmentation of Forest: The Hoolock Gibbon Sanctuary is divided into halves, segregation the population of the species, due to the construction of a railway line.
  • Electrification and expansion of rail and road infrastructure
  • Hunting 

Enroll now for UPSC Online Classes

DOWNLOAD PDF