Tinsukia: A critically endangered Western Hoolock Gibbon was electrocuted inside the Hollongapar Gibbon Wildlife Sanctuary on February 8 (HGWS) after coming into contact with a 25 KV electrified railway line, marking the first reported casualty since the project was approved through the primate habitat in 2024.
The incident occurred within the 20.98-square kilometre sanctuary, India’s only ape habitat, reigniting concerns over inadequate mitigation measures and growing habitat fragmentation.
The electrification of a 1.65-kilometre railway stretch passing through the sanctuary was cleared by the standing committee of the National Board of Wildlife (NBWL) on October 9, 2024. The project included diversion of nine hectares of forest land and a portion of the eco-sensitive zone.
Despite repeated warnings from primatologists and conservationists, the project proceeded with assurances of mitigation measures, including canopy bridges, speed restrictions, and monitoring mechanisms.
Forest officials confirmed that the male gibbon was found dead roughly 30 metres from a newly constructed canopy bridge. Natural canopy connections had previously been removed during installation of electric poles, increasing the risk for arboreal species that rely on continuous tree cover for movement. Camera traps have now been installed to monitor primate activity near the electrified line.
The sanctuary is home to about 125 Western Hoolock Gibbons, divided into 26 groups, according to the 2023 census. The railway line splits the habitat into two sections, isolating four gibbon families in the northern compartment from the rest in the south. As a monogamous and territorial species, gibbons frequently travel long distances across tree canopies to find mates, making connectivity crucial for genetic diversity and survival.
Electrification has heightened risks not only for gibbons but also for capped langurs, Malayan giant squirrels, and elephants inhabiting the sanctuary. Conservation groups have renewed calls to reroute the railway line outside the protected area, noting that the short stretch could be diverted through adjoining non-forest land, balancing infrastructure development with wildlife conservation.
With Western Hoolock Gibbon populations declining sharply over the past three decades and global numbers estimated at fewer than 5,000, this latest death underscores mounting pressure on one of the world’s most endangered primates.