A day after tiger census declared a 30 per cent jump in big cat population, a wildlife expert group questioned the procedure India adopted for the estimation, saying the method used cannot yield “sufficiently refined results” to accurately measure changes in tiger numbers.
The Wildlife Conservation Society (WCS) India, one of the NGO partners involved in the 2014 national tiger estimation effort in Karnataka, Wayanad-Kerala and Goa, said that the procedure is not the “best currently available methodology” for this task.
“We are of the view that the regression or calibration based double-sampling approach which was originally developed in 1938 and applied every four years since 2006 to Indian tiger surveys for estimating tiger numbers and distribution at landscape, regional and state levels, is not the best currently available methodology for this task.
“We do not believe this method can yield sufficiently refined results to accurately measure changes in tiger numbers at landscape or country-wide scales as is being attempted,” said K Ullas Karanth, Director of Science, Asia WCS, and Director of Centre for Wildlife Studies (CWS), today.
The statement comes a day after the Environment Ministry released the latest census report saying the tiger population in the country has risen to 2,226 in 2014, a 30 per cent increase since the last count in 2010.
The government has used the “refined methodology of double-sampling using camera traps” for the big cat population estimation.
In the double-sampling methodology, two sets of data are combined to estimate tiger numbers - first by photographing tigers through cameras and then counting of paw-marks and scat (droppings).
Mr Karanth said that alternative “superior” methods based on occupancy modeling approaches have already been demonstrated
and published which have evolved strongly after the year 2000.
“We believe that these alternatives are more cost-effective and should be implemented instead of the currently used double-sampling approach,” he said.
He said that any such distribution or occupancy surveys across country-wide scale conducted once in four years are only useful for answering “where are the tigers, rather than for estimating their numbers”.
“Primarily, such distribution surveys are useful for identifying new populations that are established or populations that are lost,” Mr Karanth said.
The total number of tigers was estimated to be around 1,706 in 2010. Tiger population had dipped to an alarming 1,411 in 2006 but has improved since then.
He said that out of 380,000 sq km of existing forests in which tigers once occurred, less than 200,000 sq km is currently occupied by tigers as per his organisation’s estimate.
He said that out of this, only 20 per cent area supports reasonable tiger densities harboring over 90 per cent of India’s tigers. However, after India launched Project Tiger in 1973, despite arresting the imminent extinction of the tiger, it has not been able to substantially increase tiger numbers in the last 42 years.
“Therefore, it is critical to expand the habitats holding these tiger source populations. With strong cooperation among governments at the Centre and states and the non-governmental sector, there is no reason why we cannot aspire to eventually have 5000 or even 10,000 wild tigers in India,” he said.
Karanth said that following the Sariska debacle, after 2006 major funding and focus have been invested by the central government to support tiger recovery and even some states have used these funds effectively and put substantial efforts into enhanced patrolling and protection, promoting voluntary village relocations, and expanding tiger reserves or adding new reserves.
He said that Karnataka, Madhya Pradesh, Maharashtra, Uttarakhand and Assam have led in these efforts and even the non-governmental sector has played an increasing and substantial role in supporting tiger conservation.
“As a consequence of all these positive efforts, the status of tigers has generally improved as concluded by the preliminary report. However, the degree and extent of this population recovery requires closer examination of detailed data from the survey,” he said.
