This story is part of The Better India’s new wildlife series, Species in Focus: 52 species. 52 stories. 52 reasons to protect India’s wildlife. One species at a time, the series explores India’s rare, endangered and lesser-known wildlife, their habitats, behaviour, ecological roles and conservation status.
Did you know that India’s mountain langurs are not all the same species?
The Himalayan grey langur, Semnopithecus schistaceus, is often confused with the Kashmir grey langur, Semnopithecus ajax.
The Himalayan grey langur may look familiar. Its long tail, grey coat and dark face place it among India’s recognisable langurs.
Current Indian mammal references treat them as separate species. But the distinction has been debated by researchers, with some genetic and morphological studies arguing that several Himalayan langur forms should instead be grouped as Himalayan grey langurs
For the Himalayan grey langur, one of the most eastern records in India is Buxa Tiger Reserve in northern West Bengal, extending at least to the Raidak River.
The species occurs across the Himalaya, including parts of northern India, Nepal, Bhutan and Tibet. It uses both trees and the ground and is primarily a leaf-eater.
But long before Buxa entered the picture, researchers were struggling to understand its western Himalayan relatives.
A species once split into several
For much of the 20th century, Himalayan langurs were classified under different names and subspecies. S ajax, S schistaceus and other forms were separated largely on physical characteristics.
A 2020 study by researchers from the Indian Institute of Science and the Wildlife Institute of India used morphology, DNA and ecology to examine the question.
The researchers concluded that the Himalayan langur was different from the plains Hanuman langur, Semnopithecus entellus, but found no evidence supporting multiple Himalayan subspecies. They recommended Semnopithecus schistaceus as the species name for the Himalayan langur.
Other researchers have continued to treat S. ajax as a separate species. That is why the names still appear differently across databases and research papers.
From forests to villages
The Himalayan grey langur occupies a wide elevational range, from around 1,500 to 4,000 metres, across mountain forests and associated habitats.
Its ability to live across such elevations means its diet changes with the landscape.
It is primarily folivorous, feeding on leaves and other plant material.
The animal has a grey coat, dark face, long limbs and a long tail. Males can develop a pronounced mane around the shoulders. Photograph: (Nature inFocus-Himani Nautiyal)
A 2024 study in the American Journal of Primatologyexamined female social dynamics and grooming networks in Central Himalayan langurs. The research followed groups of S. schistaceus and looked at how social relationships are structured through grooming, an important behaviour in primates.
The species is not restricted to untouched forests either.
Researchers working in northern India have documented Himalayan grey langurs occurring alongside human-dominated landscapes. A 2025 study of rhesus macaques in northern India noted occasional Himalayan grey langurs in a landscape where forests were interspersed with villages, agricultural fields, roads, temples and other human structures.
Why winter matters for a langur living in the Himalaya
The seasons determine what the forest can provide.
At higher elevations, winter means lower temperatures and changes in vegetation. The species’ reliance on leaves and other plant matter makes forest composition important throughout the year.
Its physical appearance also reflects its mountain habitat. The animal has a grey coat, dark face, long limbs and a long tail. Males can develop a pronounced mane around the shoulders.
What happens when forests fragment?
The Himalayan langur’s range crosses national boundaries and different kinds of landscapes. That makes habitat connectivity important.
Genetic research on Himalayan langurs in Nepal has found spatial structure between populations and suggested that rivers and geography can influence gene flow.
The species’ eastern Indian limit at Buxa is therefore significant. Buxa forms part of the Himalayan forest system that connects India’s northeastern landscape with the wider Himalayan region.
In Buxa, across the central Himalaya and into Nepal, understanding which langur lives where is the first step towards understanding what it needs.
And for an animal living across forests divided by elevation, geography and human landscapes, keeping those connections intact may matter as much as counting the animals themselves.
