Losing ground: tigers Panthera tigris in the north-western Shivalik landscape of India

Abstract

Rajaji National Park, which forms the north-western limit of the range of the tiger Panthera tigris in India, is bisected into western and eastern sectors by development activities along the banks of the river Ganga. Following a voluntary pastoral Gujjar resettlement programme initiated in the Park by the Uttarakhand Forest Department, we assessed the status of the tiger and its prey. We used sign surveys for tigers, leopards Panthera pardus and their prey, estimated prey densities using line transects and distance sampling, and estimated the density of tigers using photographic capture-recapture analysis. Our results indicate that the use of the area by tigers differed significantly between the two sectors of the Park, with pug mark encounter rates per 250 m segment from sign surveys of 0.07 ± SE 0.04 in the west and 1.6 ± SE 0.3 in the east. Although the high estimated prey densities (> 80 km-2) in the Park have the potential to support high densities of tigers, we photo-captured only one tigress in the western sector and five adult tigers and two cubs in the east (the latter with a mean density of 5.12 ± SE 0.7 per 100 km2). Whereas recovery of the tiger population in the eastern sector following the resettlement of Gujjars is evident, the lack of connectivity to source populations (Corbett Tiger Reserve and eastern Rajaji National Park) and increased anthropogenic pressures appear to have inhibited the recovery of tiger populations in the western sector. Restoration, therefore, of the Chilla-Motichur corridor to facilitate the dispersal of tigers from the eastern to the western sector of the Park is of critical importance.