Pallava Bagla Science Magazine 29 Mar 11;
A new survey by the Indian government reports a 12% increase in the country's adult tiger population. But some tiger experts think the numbers don't really add up.
A 2006 survey estimated that the country was home to 1165 to 1657 tigers. The latest survey counts 1571 to 1875 tigers, almost 60% of the world's wild population, including 70 tigers that were found in the mangroves of the Ganges Delta of the Sundarbans, an area not covered during the last survey, and another 30 from two other areas—the Orang Wildlife Sanctuary in eastern India and the Sahyadari protected area in western India—that were left out earlier. However, tigers are now squeezed into 22% less space than 5 years ago, to some 72,000 square kilometers today.
The data, released yesterday by India's environment minister, Jairam Ramesh, comes from an 18-month, $2.1 million survey that involved 476,000 people looking for the animals and their scat, some of which was used for DNA analyses. In addition, 800 camera traps caught passing tigers digitally.
Yadavendra V. Jhala, a wildlife biologist at the Wildlife Institute of India in Dehradun, who spearheaded the exercise, says he was expecting a drop in population and was pleasantly surprised by the higher tally. Ramesh expressed "happiness" with the results but cautioned, "it is really a mixed bag out there, since the threats to the tiger are very imminent, including poaching and habitat loss." The greatest threat is the loss of corridors that connect the 39 tiger reserves India legally protects, Ramesh noted.
James Leape, an environmental lawyer and director general of WWF International in Gland, Switzerland, calls the results "very encouraging." Leape says they demonstrate that "wherever protection is good, tigers will thrive."
Yet not everybody is buying into this new roar of the tiger. "The habitat of the tiger has only shrunk, poaching has increased, and conservation has been diluted, so how can the numbers of tigers increase?" says P. K. Sen, former director of Project Tiger. He calls the new figures "statistical jugglery." And K. Ullas Karanth, a veteran tiger biologist at the Wildlife Conservation Society in New York City, worries that the survey methodology was flawed and that the sample size was too small.
Jhala defends his work, noting that "615 individual tigers were captured in the camera traps, which represent almost a third of the total tiger population, so the extrapolation is not only accurate but statistically robust." The details of the survey will be released in 3 weeks.
