Estimating the abundance of Nepal's largest population of tigers <i>Panthera tigris</i>

<jats:title>Abstract</jats:title><jats:p>Information on the abundance of tigers <jats:italic>Panthera tigris</jats:italic> is essential for effective conservation of the species. The main aim of this study was to determine the status of tigers in Chitwan National Park, Nepal, including the Churia hills, using a camera-trap based mark–recapture abundance estimate. Camera traps (n = 310) were placed in an area of 1,261 km<jats:sup>2</jats:sup> from 20 January to 22 March 2010. The study area was divided into three blocks and each block was trapped for 19–21 days, with a total effort of 3,582 man-days, 170 elephant-days and 4,793 camera-trap nights. The effectively camera-trapped area was 2,596 km<jats:sup>2</jats:sup>. Camera stations were located 1.5–2 km apart. Sixty-two tigers (age ⩾ 1.5 years), comprising 15 males, 41 females and six of unidentified sex, were identified from 344 photographs. The heterogeneity model Mh (jackknife) was the best fit for the capture history data. A capture probability (<jats:inline-formula><jats:alternatives><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0030605313000471_inline1" /><jats:tex-math>$\hat P$</jats:tex-math></jats:alternatives></jats:inline-formula>) of 0.05 was obtained, generating a population estimate (<jats:inline-formula><jats:alternatives><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:type="simple" xlink:href="S0030605313000471_inline2" /><jats:tex-math>$\hat N$</jats:tex-math></jats:alternatives></jats:inline-formula>) of 125 ± SE 21.8 tigers. The density of tigers in the area, including Churia and Barandabhar (buffer zone forest linked with mid hill forest), was estimated to be 4.5 ± SE 0.35 tigers per 100 km<jats:sup>2</jats:sup>, using a Bayesian spatially explicit capture–recapture model in <jats:italic>SPACECAP</jats:italic>. Our study showed the use of Churia by tigers and we therefore conclude that the Chitwan tiger population serves as a source to maintain tiger occupancy of the larger landscape that comprises Chitwan National Park, Parsa Wildlife Reserve, Barandabhar buffer zone, Someswor forest in Nepal and Valmiki Tiger Reserve in India.</jats:p>