Post-translocation population characteristics and conservation insights for eastern swamp deer Rucervus duvaucelii ranjitsinhi reinforcement in Manas National Park, Assam, India

Sci Rep. 2026 May 12. doi: 10.1038/s41598-026-47550-2. Online ahead of print.

ABSTRACT

The eastern swamp deer (Rucervus duvaucelii ranjitsinhi), a vulnerable cervid subspecies, is currently restricted to only Kaziranga and Manas National Parks in Assam, India. Extensive hunting and poaching during the 1980s civil unrest reduced its Manas population to fewer than 20 individuals. To reinforce the remnant population, 36 individuals were translocated from Kaziranga to Manas between 2014 and 2017. Post-translocation monitoring from 2017 to 2023, using systematic scan sampling and block count methods, revealed that the eastern swamp deer population increased to 174 individuals, achieving an ecological density of 1.65 individuals per km². The mean group size (6.86 ± 4.32) comprised 21% adult males, 56% adult females, 14% sub-adults, and 9% fawns. An annual mean population growth rate of 17.13% indicates successful establishment and recovery of the subspecies in the Manas landscape. While late-season grassland burning threatens habitat quality by promoting invasive plant species and overlapping breeding periods; controlled early patch burning (November-December) is recommended to avoid fawning period, retain soil moisture, and support sustainable grassland regeneration. Long-term conservation of the eastern swamp deer requires the protection and restoration of grasslands, swamps, and water bodies alongside enhanced anti-poaching measures and sustained ecological monitoring for population resilience in the Manas landscape.

PMID:42120442 | DOI:10.1038/s41598-026-47550-2