A deadly conflict
In the middle of the vast Brahmaputra River in Assam, just off the sprawling city of Guwahati, there’s a tiny, wooded island little more than 100 metres from one end to the other. Called Umananda, it’s chiefly renowned locally for the temple which is dedicated to the Hindu god Shiva and was originally built at the end of the 17th century.
In the 1980s, a Hindu priest built another temple, this one for the monkey god Hanuman, and this priest then took it upon himself to introduce a young pair of what he thought were Hanuman langurs, a primate with distinctive silver grey hair that’s found throughout a large area of eastern India.
But these monkeys were actually golden langurs, a much rarer species entirely restricted to the state of Assam and southern Bhutan. At the time, the island was also home to a small troop of western hoolock gibbons, and in 1996, Dr Jihosuo Biswas had decided to study this small population of almost equally rare apes while carrying out research for his Master’s dissertation.
But this wasn’t to be. ‘Upon reaching the island, I discovered that the gibbons I had anticipated studying had unfortunately died,’ Jihosuo recalls. In fact, it was worse than that – the release of the langurs had sparked a deadly conflict between the two species.
As it turns out, gibbons and langurs occupy the same niche – the forest canopy – and eat the same foods, and during a confrontation between them, the female gibbon died.
‘Overwhelmed, isolated and gripped by fear, the male gibbon met a poignant end by drowning in the river,’ Jihosuo reports, ‘underscoring the challenges that can arise when species with similar needs are forced into proximity.’
His plans for the gibbons thwarted, Jihosuo decided instead to gather data on the ecology of the golden langurs, which were very poorly studied because of security issues in northern Assam where they’re mainly found.
Jihosuo eventually returned to studying the western hoolocks, but over the years he’s also engaged in research on many primates, including various species of macaques, capped lemurs and the Bengal slow loris – as well as golden langurs. Today he’s one of the few acknowledged experts in the world on this vanishingly rare monkey, which has been assessed by the IUCN’s Primate Specialist Group as one of the 25 most endangered primates on the planet.
And it’s Jihosuo’s expertise, and his plans for securing and restoring populations of both the gibbons and the langurs, that has persuaded PTES to take him on as our new Conservation Partner. With their extremely restricted range, golden langurs, especially, need all the help we can give them.
Monkey warriors
Within India, surveys carried out by Biswas and his colleagues have put their population at a little over 7,000 individuals (there are thought to be another 2,500 in Bhutan), and they’re divided into two distinct groupings. One is located in the Manas Biosphere Reserve in the north-west corner of Assam bordering Bhutan. Then there’s a more southerly population that’s split into numerous forest fragments on the northern side of the Brahmaputra River.
‘Discovered in the 1950s, golden langurs were once abundant in the forests of their known distribution range in northwestern Assam,’ Jihosuo says. At the time, ‘local communities coexisted harmoniously with them and other wildlife due to their traditional practices and interest in conservation,’ he adds.
But Jihosuo goes on: ‘Since the 1970s, however, extensive forest destruction, stemming from unrest and the conversion of forest land for agriculture and compounded by immigration from neighbouring countries, has led to a 50 per cent reduction in its primary habitat.’
More recently, the construction of highways and other infrastructure has led to other challenges for the langurs – most notably, the risk of being killed by vehicles when they attempt to cross the roads, but also electrocution on electric lines.
To reduce these impacts, Jihosuo and his colleagues came up with the idea of building canopy bridges over one of the major trunk roads that bisects the habitat of the southerly population.
‘Up to this point, we have set up four ladder-type bridges, two rope bridges, one bamboo bridge and one pipe bridge,’ Jihosuo says. ‘Additionally, we’ve placed five camera traps on the bridges to monitor the movements of the langurs.’
Jihosuo’s team is also encouraging community-based tree-planting to create forest corridors between villages. The aim is to select trees that have a commercial value for local people, so that the conservation efforts align with socio-economic interests. Jihosuo says they’ve so far planted 1,000 saplings, with another 4,000 to go, which will help create two village corridors.
In addition, Jihosuo uses these same people to help him in his work by training them to monitor the langurs, calling them ‘Sugriv Sena’ or monkey warriors. This is important partly to foster tolerance of the langurs, which occasionally come into villages to feed on their crops.
Positive news for the primates
PTES funding will also help support Jihosuo’s hoolock gibbon conservation efforts. Like the golden langurs, this species is largely concentrated in Assam, which accounts for about 70 per cent of those found in India, though there are also populations in Bangladesh, Myanmar and possibly China.
The work will take place in what’s known as the Joypur-Dirak-Upper Dehing Priority Forest Complex in the far east of Assam, with the newly designated Dehing Patkai National Park a core component. ‘The national park has been elevated with a primary emphasis on the hoolock gibbon as a flagship species,’ Jihosuo says.
He aims to help officials develop a management plan for the park, improve the capacity of front-line forest staff and design and implement community-based gibbon-monitoring and conservation education programmes. These will also focus on the slow loris, another important species in the area.
In the long-run, habitat loss and fragmentation are likely to continue to cause significant issues for both golden langurs and hoolock gibbons. The more this happens, the more it’s likely to increase the incidence of animals straying into village areas and coming into conflict with farmers as a result of crop-raiding. Extreme weather conditions, brought on by our changing climate, could disrupt food supplies and exacerbate human-wildlife conflict.
But it’s not all bad news. In 2021, for example, Raimona National Park was created with golden langurs as the flagship species, while nearby Dehing Patkai National Park was designated specifically for the hoolock gibbons. This park is a biodiversity hotspot, with the highest number of primate and cat species in all of North-east India.
It helps that golden langurs are not hunted in India because the species is represented in a Hindu text called the Ramayana as the monkey king, Sugriva. This, Jihosuo explains, gives communities some attachment to the species.
Over the coming years, we hope Jihosuo and his team will increase that attachment still further, thereby securing the future of this precious primate and its distant cousin, the gregarious gibbon.
Learn more about Jihosuo’s work protecting golden langurs and hoolock gibbons:
Header image: A golden langur monkey by Anuradha Marwah, www.shutterstock.com