Hoolock gibbons and golden langurs

Study species: Hoolock gibbons and golden langurs

Project location: India

Species fact: Golden langur monkeys are found in the Assam region in Northeastern India and in southern Bhutan and are considered sacred by Himalayan people. With their flowing coats and black faces, golden langurs are one of the world’s most striking and beautiful monkeys, but with fewer than 10,000 individuals left in the world, they’re close to extinction. 

Western hoolock gibbons are an endangered lesser ape found across Asia, though 70% of the Indian population are in Assam. Males are black with a distinctive white eyebrow-like stripe above their eye, whereas females are much lighter in colour, usually beige, with dark brown hair on the sides of their face. They form monogamous pairs and will sing in unison to mark their territory.  

Problem: Sadly, habitat loss is severely threatening golden langurs. The Assam region has lost almost one half of its forest in the last few decades. The remaining populations of golden langurs now exist in isolated pockets of forest, and must travel across farmland, villages and roads to find food and mates. Their numbers in Bhutan have also declined in the past three decades. As a result, the IUCN Primate Specialist Group listed golden langurs as one of the ‘25 most endangered primates in the world’ in 2016-18 and again in 2018-2020. 

Western hoolock gibbons are threatened with habitat loss and hunting throughout their range. In Assam the population has dramatically declined by 90% in recent years.