IUCN / SSC Cat Specialist Group - Digital Cat Library
   

 

View printer friendly
Sharma, R.K.; Jhala, Y.; Qureshi, Q.; Vattakaven, J.; Gopal, R.; Nayak, K.
Evaluating capture-recapture population and density estimation of tigers in a population with know parameters
2010  Animal Conservation (13): 94-103

Conservation strategies for endangered species require accurate and precise estimates of abundance. Unfortunately, obtaining unbiased estimates can be difficult due to inappropriate estimator models and study design. We evaluate population-density estimators for tigers _Panthera tigris_ in Kanha Tiger Reserve, India, using camera traps in conjunction with telemetry (n=6) in a known minimum population of 14 tigers. An effort of 462 trap nights over 42 days yielded 44 photographs of 12 adult tigers. Using closed population estimators, the best-fit model (program CAPTURE) accounted for individual heterogeneity (Mh). The least biased and precise population estimate (n (SE) [n]) was obtained by the Mh Jackknife 1 (JK1) [14 (1.89)] in program CARE-2. Tiger density ( D (SE) [ D]) per 100km2 was estimated at 13 (2.08) when the effective trapping area was estimated using the half mean maximum distance moved (1/2 MMDM), 8.1 (2.08), using the home-range radius, 7.8 (1.59), with the full MMDM and 8.0 (3.0) with the spatial likelihood method in program DENSITY 4.1. The actual density of collared tigers (3.27 per 100km2) was closely estimated by home-range radius at 3.9 (0.76), full MMDM at 3.48 (0.81) and spatial likelihood at 3.78 (1.54), but overestimated by 1/2 MMDM at 6 (0.81) tigers per 100km2. Sampling costs (Rs. 450 per camera day) increased linearly with camera density, while the precision of population estimates leveled off at 25 cameras per 100km2. At simulated low tiger densities, a camera density of 50 per 100km2 with an effort of 8 trap nightskm2 provided 95% confidence coverage, but estimates lacked precision.

PDF files are only accessible to Friends of the Cat Group. Joining Friends of the Cat Group gives you unlimited access and downloads in the Cat SG Library for one year, and allows you to receive our newsletter Cat News (2 regular issues per year plus special issues). More information how to join here

 

(c) IUCN/SSC Cat Specialist Group ( IUCN - The World Conservation Union)