A new peer-reviewed paper by the Wildlife Conservation Society and other groups reveals an ominous finding: most of the world's last remaining tigers -- long decimated by overhunting, logging, and wildlife trade -- are now clustered in just six percent of their available habitat. The paper identifies 42 'source sites' scattered across Asia that are now the last hope and greatest priority for the conservation and recovery of the world's largest cat.

The securing of the tiger's remaining source sites is the most effective and efficient way of not only preventing extinction but seeding a recovery of the wild tiger, the study's authors say. The researchers also assert that effective conservation efforts focused on these sites are both possible and economically feasible, requiring an additional $35 million a year for increased monitoring and enforcement to enable tiger numbers to double in these last strongholds.

The study -- published online by PLoS Biology -- is authored by: Wildlife Conservation Society researchers Joe Walston, John Robinson, Elizabeth Bennett, John Goodrich, Melvin Gumal, Arlyne Johnson, Ullas Karanth, Dale Miquelle, Anak Pattanavibool, Colin Poole, Emma Stokes, Chanthavy Vongkhamheng, and Hariyo Wibisono; Urs Breitenmoser of the IUCN/SSC Cat Specialist Group; Gustavo Fonseca of the Global Environment Facility (GEF); Luke Hunter and Alan Rabinowitz of Panthera; Nigel Leader-Williams of the University of Cambridge; Kathy MacKinnon of the World Bank; Dave Smith of the University of Minnesota; and Simon Stuart, Chair of the IUCN's Species Survival Commission

"While the scale of the challenge is enormous, the complexity of effective implementation is not," said Joe Walston, Director of the Wildlife Conservation Society's Asia Program and lead author of the study. "In the past, overly ambitious and complicated conservation efforts have failed to do the basics: prevent the hunting of tigers and their prey. With 70 percent of the world's wild tigers in just six percent of their current range, efforts need to focus on securing these sites as the number one priority for the species."

According to the paper, fewer than 3,500 tigers remain in the wild, of which only about 1,000 are breeding females. Walston and his co-authors identified 42 tiger source sites, which were defined as sites that contain breeding populations of tigers and have the potential to seed the recovery of tigers across wider landscapes.

India was identified as the most important country for the species with 18 source sites. Sumatra contains eight source sites, and the Russian Far East contains six.

The authors calculate the total required annual cost of effectively managing source sites to be $82 million, which includes the cost of law enforcement, wildlife monitoring, community involvement, and other factors. However, much of that is already being provided by range state governments themselves, supplemented by international support. The shortfall -- $35 million -- is needed to intensify proven methods of protection and monitoring on the ground.

"The tiger is facing its last stand as a species," said Dr. John Robinson, Executive Vice President of Conservation and Science for the Wildlife Conservation Society. "As dire as the situation is for tigers, the Wildlife Conservation Society is confident that the world community will come together to save these iconic big cats from the brink for future generations. This study gives us a roadmap to make that happen."

Dr. Gustavo Fonseca, team leader of natural resources at the Global Environment Facility, said: "A key goal for us is to help identify the most efficient path forward so countries can achieve their global biodiversity conservation objectives. The GEF is pleased to have been able to contribute to this initial assessment focusing on the highest priority sites for the future of this magnificent species"

Alan Rabinowitz, President and CEO of Panthera, said: "We know how to save tigers. We have the knowledge and the tools to get the job done. What we are lacking is political will and financial support. The price tag to save one of the planet's great iconic species is not a high one."

The authors say that in spite of decades of effort by conservationists, tigers continue to be threatened by overhunting of both tigers and their prey, and by loss and fragmentation of habitat. Much of the decline is being driven by the demand for tiger body parts used in traditional medicines.