Status of the Tigers, co-predators, and prey in India 2010

Abstract

This report synthesizes the results of the second countrywide assessment of the status of tigers, co-predators and their prey in India. The first assessment was done in 2006 and its results subsequently helped shape the current policy and management of tiger landscapes in India. The current report is based on data collected in 2009-2010 across all forested habitats of 17 tiger States of India with an unprecedented effort of about 477,000 man days by forest staff, and 37,000 man days by professional biologists. The results provide spatial occupancy, population limits, and abundance of tigers, habitat condition and connectivity (Fig E1). This information is crucial for incorporating conservation objectives into land use planning across landscapes so as to ensure the long term survival of free ranging tigers which serve as an umbrella species for the conservation of forest biodiversity. The study reports a countrywide increase of 20% in tiger numbers but a decline of 12.6% in tiger occupancy from connecting habitats. The methodology consisted of a double sampling approach wherein the State Forest Departments estimated occupancy and relative abundance of tigers, co-predators, and prey through sign and encounter rates in all forested areas (Phase I). Habitat characteristics were quantified using remotely sensed spatial and attribute data in a geographic information system (Phase II). A team of trained wildlife biologists then sampled a subset of these areas with approaches like mark-recapture and distance sampling to estimate absolute densities of tigers and their prey (Phase III), using the best modern technological tools (remote camera traps, GPS, laser range finders). A total effort of 81,409 trap nights yielded photo-captures of 635 unique tigers from a total camera trapped area of 11,192 km2 over 29 sites. The indices and covariate information (tiger signs, prey abundance indices, habitat characteristics) generated by Phase I & II were then calibrated against absolute densities using Generalized Linear Models (GLM) and the relationships were used for extrapolating tiger densities within landscapes. Tiger numbers were obtained for contiguous patches of occupied forests by using average densities for that population block. Numbers and densities were reported as adult tigers with a standard error range. Habitat suitability for tigers was used to model least cost pathways joining tiger populations in a GIS and alternative routes in Circuit scape. These were aligned on high-resolution satellite imagery to delineate potential habitat corridors