Guwahati: In a rare story of ecological revival following civil unrest, a comprehensive study conducted in Manas National Park has revealed a remarkable resurgence of endangered prey and predator species.
Using advanced monitoring techniques, researchers found that more than two decades after armed conflict devastated wildlife populations and park infrastructure, Manas is regaining its lost biodiversity, setting an example for post-conflict conservation worldwide.
Situated at the confluence of the Indo-Burma and Himalayan biodiversity hotspots, Manas suffered heavily from armed insurgency between the late 1980s and early 2000s. The unrest led to the near-collapse of park management, rampant poaching, and the local extinction of iconic species like the greater one-horned rhinoceros and eastern swamp deer. Tigers, elephants, and wild buffalo were also severely affected.
However, recent findings from a joint study by the Wildlife Institute of India, the National Tiger Conservation Authority, and forest staff of the Manas Tiger Reserve, using elephant-back line transects and camera-trap-based spatial capture-recapture surveys, show signs of significant wildlife recovery.
The study, carried out in 2022 and 2023, found the density of Asian elephants in Manas to be 9.14 individuals per square kilometre—among the highest reported globally. A total of 267 camera trap stations were deployed during the sampling period in Manas, resulting in 10,497 trap nights of effort. Fifty-seven adult tigers (26 females, 23 males, 8 unsexed) and 38 individual leopards (18 females, 14 males, 6 unsexed) were identified from 543 and 177 detections, respectively.
“This study provided the first robust baseline estimate for the elephant population in Manas, revealing one of the highest elephant densities in the world, exceeding those reported in previous studies. The consistency of these density estimates across two consecutive years (2022 and 2023) during the same season underscores the reliability of the elephant-back line transect distance sampling model. This high elephant density likely reflects seasonal congregation due to post-burn grassland regrowth, the high water tables, and the migration to Manas within the landscape, as the park’s role as a critical node in the larger Eastern Himalayan landscape facilitates transboundary elephant movements with Bhutan and West Bengal,” the authors say.
Similarly, wild buffalo densities reached 4.47 per sq km, while the tiger population stood at an impressive 7.91 adults per 100 sq km. The wild buffalo, an endangered grassland megaherbivore, has over 90% of its global population concentrated in Manas and Kaziranga Tiger Reserves. While remaining populations within its global range are on the brink of extinction, the present density estimate suggests that Manas likely harbours the highest density of wild buffalo globally.
A total of 57 adult tigers, including over 20 breeding females, were recorded, signalling a healthy and growing population. The recovery of the tiger population in Manas is driven by enhanced protection measures, such as improved law enforcement and increased prey availability.
“With 57 adult individuals, including more than 20 breeding females, Manas serves as a critical source population for the transboundary Manas-Dooars landscape. Population recovery often leads to natural dispersal into previously unoccupied areas. The movement of tigers from Manas to Buxa Tiger Reserve in West Bengal and Bornadi Wildlife Sanctuary in Assam (easternmost part of Manas Tiger Reserve) highlights the ongoing recolonisation of former habitats, further emphasising the preservation and importance of ecological corridors in the Eastern Himalayan foothills,” the study says.
Reintroduced species have shown particularly promising trends. The rhinoceros and swamp deer populations, both reintroduced in 2008 and 2014, respectively, are growing at a steady rate of 17% annually. These recoveries underscore the effectiveness of focused post-conflict rewilding efforts.
Despite the overall good news, not all species are faring well. The hog deer population, once abundant in the region and a key prey species for tigers, has declined by over 80% since 2015. Wild pig densities also dropped significantly, likely due to persistent bushmeat hunting. Conservationists warn that such prey loss could trigger a “predator pit” effect, where insufficient prey density leads to stagnating predator populations.
The authors advocate for immediate action to rescue hog deer populations, including translocation from other reserves like Orang and Kaziranga, and establishing predator-proof safety enclosures.
The authors say the ecosystem resilience demonstrated by Manas National Park following prolonged socio-political instability highlights the importance of sustained conservation investment following conflict resolution.
“Our study showed that law enforcement strengthening, community engagement, restoration of governance, and the use of digital monitoring tools such as M-STrIPES (Monitoring System for Tigers – Intensive Protection and Ecological Status) were crucial in supporting the recovery of endangered species,” the authors say.
The authors note that India uses an umbrella species conservation approach, where the recovery of the apex species is often evaluated as an indicator of overall ecosystem health, including improvements in the status of other species in the lower trophic orders.
“However, our study emphasises that such an approach alone may not always cater to the needs of habitat specialist species, e.g. hog deer in Manas. There is an urgent need to initiate population augmentation programmes for hog deer through translocation from Tiger Reserves such as Orang and Kaziranga, and a safe population should be kept in predator-proof fencing. In addition, the reduction of the wild pig, which is also a major prey for large carnivores, reasserts the need to strengthen habitat protection,” the authors say.
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