A recent scientific analysis of lion-tailed macaques (Macaca silenus) across fragmented landscapes of the Western Ghats has produced an unexpected finding. Instead of declining uniformly, several populations of this endangered primate are holding steady and, in some locations, even increasing within plantation-dominated terrains and isolated forest fragments. Long-term demographic comparisons from the Anamalai landscape of Tamil Nadu show that population trends vary sharply between intact rainforests and human-modified habitats, with some plantation-embedded fragments sustaining viable multi-group populations for decades.
Researchers attribute this persistence to behavioural flexibility, adaptive ranging patterns and the continued presence of remnant canopy patches that function as ecological lifelines. “We expected many of these fragment populations to disappear over time, but some have remained surprisingly stable,” notes a research paper published in the latest issue of the Journal for Nature Conservation. “This indicates that the species possesses more resilience than earlier assumed, although the situation remains fragile.”
The long-term study was led by G Umapathy, Chief Scientist at the Centre for Cellular and Molecular Biology’s Laboratory for Conservation of Endangered Species (LaCONES). The research team included Sanatanu Mahato and H N Kumara of the Salim Ali Centre for Ornithology and Natural History, Coimbatore, along with Mrudala Singh and Mewa Singh of the University of Mysore.
Despite these encouraging findings, scientists caution that the species is far from secure. Only a few thousand individuals are believed to survive across the Western Ghats, and long-term threats such as habitat fragmentation, infrastructure expansion and increasing human-wildlife interaction continue to shape its future.
The lion-tailed macaque, one of India’s most distinctive primates, is endemic to the evergreen forests of the Western Ghats. Highly arboreal and dependent on complex rainforest canopies for movement and feeding, the species was historically considered extremely vulnerable to habitat fragmentation. Early conservation thinking assumed that survival depended almost entirely on large, continuous tracts of undisturbed forest.
The principal population strongholds continue to lie in the Nilgiri-Silent Valley landscape, the Anamalai-Parambikulam complex, the Sharavathi Valley in Karnataka and the Agasthyamalai ranges spanning southern Kerala and Tamil Nadu. Among these, Silent Valley National Park remains one of the most important refuges, preserving extensive stretches of undisturbed rainforest that support breeding populations.
However, surveys over the past two decades have revealed a more complex ecological reality. Several troops now inhabit small rainforest fragments surrounded by tea, coffee and rubber estates. In certain landscapes, the number of troops has remained stable for decades and, in some cases, has even increased as dispersing groups establish themselves in new fragments.
“Fragmentation does not always mean immediate extinction,” conservation biologists working in the Anamalai region observe. “If fragments retain native trees, some degree of canopy connectivity and low hunting pressure, the animals can survive for long periods. But this stability should not be mistaken for long-term recovery.”
The Valparai plateau in the Anamalai Hills has become a key landscape for understanding primate survival in fragmented habitats. Here, dozens of rainforest fragments, some only a few hectares in size, are scattered across a plantation-dominated terrain. Conventional ecological theory once predicted that such isolated patches would be incapable of sustaining long-term primate populations. Instead, monitoring studies show that several lion-tailed macaque troops have survived in these fragments for more than 40 years.
Researchers say survival in Valparai depends on a combination of ecological and human factors. Native fruiting trees within fragments provide seasonal food resources, occasional canopy connections allow safer movement between patches, and targeted conservation measures such as canopy bridges across roads have reduced mortality in certain areas.
“The plantation landscape is not ideal habitat, but it is not entirely hostile either,” notes a field researcher involved in fragment studies. “Where plantation companies cooperate in protecting native vegetation and maintaining tree cover, the macaques manage to survive.”
At the same time, these landscapes expose the animals to new dangers rarely encountered in intact forests. Vehicle collisions, electrocution from power lines, attacks by feral dogs and dependence on human food waste are now recorded causes of mortality in fragmented habitats. Conservationists warn that without systematic mitigation measures, these risks could gradually offset the demographic stability observed in some regions.
The conservation history of the lion-tailed macaque is closely linked to India’s environmental movement. In the 1970s, a proposed hydroelectric project threatened to submerge large areas of pristine rainforest in the Silent Valley region of Kerala. Scientists warned that the project would destroy one of the species’ most critical habitats, triggering a nationwide campaign that brought together researchers, writers, students and local communities.
The movement eventually succeeded in halting the project and led to the declaration of Silent Valley National Park. Environmental historians often describe this episode as one of the earliest instances in which ecological science decisively shaped development policy in India. “Silent Valley showed that scientific evidence and public mobilisation could change the course of major development decisions,” recalls environmental activist Sridhar Radhakrishnan. “The lion-tailed macaque became a symbol of that transformation.”
While the movement secured one of the species’ most important habitats, conservation challenges today extend far beyond the protection of individual forests. Much of the macaque’s current range lies outside strictly protected areas, within landscapes shaped by plantations, settlements and infrastructure corridors.
Habitat fragmentation remains the most serious long-term threat facing the species. Large continuous rainforest tracts have been divided into smaller patches by plantations, roads, dams and urban expansion. For an arboreal primate dependent on canopy movement, fragmentation disrupts feeding routes, dispersal patterns and genetic exchange between populations.
Isolated troops may survive for years, but long-term genetic isolation can reduce reproductive success and resilience to environmental change. “Small populations cut off from each other gradually lose genetic diversity,” explains a wildlife geneticist studying Western Ghats primates. “Even if numbers appear stable in the short term, genetic isolation can create serious long-term risks.”
Recent demographic analyses indicate that fragmentation does not always result in immediate population collapse. In some plantation landscapes, the number of groups has increased even where average group size has declined, suggesting dispersal into new fragments rather than simple contraction. Researchers interpret this as evidence that landscape configuration, including the number, size and connectivity of forest patches, plays a critical role in determining conservation outcomes.
Kerala occupies a distinctive position in the conservation history of the Western Ghats. The state’s relatively high forest cover and the legacy of the Silent Valley movement have contributed to comparatively strong institutional awareness of biodiversity concerns. Forest officials increasingly acknowledge that conservation success will depend on addressing threats beyond protected-area boundaries.
“In the past, our focus was mainly on protecting core forests,” says Kerala’s Chief Wildlife Warden Pramod Krishnan. “Today we must manage corridors, roads, power lines and plantation landscapes where wildlife populations actually live.”
Several initiatives across parts of the Western Ghats aim to address this shift, including canopy bridges across highways, pilot projects to insulate power lines in wildlife-sensitive zones, corridor restoration programmes and collaborative conservation efforts involving plantation companies. Scientists say such landscape-level interventions will be crucial if the fragile stability observed in fragmented populations is to translate into long-term survival.
However, policy implementation remains uneven. Infrastructure expansion, tourism growth and road-widening projects continue to fragment habitats faster than mitigation measures can compensate. Conservation groups argue that environmental impact assessments must incorporate landscape-level biodiversity planning rather than focusing narrowly on individual project boundaries.
The behavioural plasticity displayed by lion-tailed macaques in fragmented habitats has attracted significant scientific attention. Troops in plantation landscapes have been observed crossing roads, using the ground more frequently than previously documented and occasionally exploiting cultivated crops or human food waste. Such flexibility has enabled survival in altered environments but also increases the likelihood of conflict and accidental mortality.
“Adaptation buys time, but it does not guarantee survival,” says environmental activist Frank Benjamin of Valparai in Tamil Nadu. “Without habitat connectivity and careful management of human activities, these populations can still decline in the long run.”
Scientists emphasise that recent findings showing population persistence in some fragmented landscapes should not be interpreted as evidence that the species is secure. Instead, they highlight the importance of integrating conservation planning into broader land-use decisions involving agriculture, infrastructure and tourism.