Celebrations in India over the revival in its tiger population may be premature and the result of a measuring error, according to a team British-India team of scientists.
India announced in January that the country was now home to 30% more tigers than four years ago, with numbers rising from 1,706 in 2010 to 2,226 in 2014.
The Indian government used calculating a technique — the Index Calibration model which measures animal numbers when they can’t all be seen, using data such as from camera-traps and radio-collars.
This technique is commonly used in censuses of tigers and other rare wildlife.
However a team of scientists from the University of Oxford, Indian Statistical Institute and Wildlife Conservation Society have exposed, for the first time, inherent shortcomings in the method that means it can produce inaccurate results.
Index-calibration often relies on measuring animal numbers accurately in a relatively small region using reliable, intensive and expensive methods (such as camera trapping) and then relating this measure to a more easily obtained, inexpensive indicator (such as animal track counts) by means of calibration. The calibrated-index is then used to extrapolate actual animal numbers over larger regions.
