Efforts to rescue the tiger from the brink of extinction should focus on protecting populations of the big cat in a few key sites, researchers urged today.
Conservationists warned the species was facing its "last stand", with fewer than 3,500 tigers in the wild - of which just 1,000 are breeding females.
But protecting 42 sites, which cover just 6% of the animal's available habitat, would directly defend almost 70% of the world's remaining tigers and should be the immediate priority for conservation efforts.
Writing in the journal PLoS Biology, the researchers said over-hunting of tigers and their prey had driven the decline in the big cat, while loss of habitat was also a factor.
The apparent success of reserves established in the 1970s to protect the tiger had led many conservation experts to shift their focus to attempts to preserve the cat well outside these protected areas.
But protection and management in reserves was inadequate and the increased demand for tiger parts for traditional medicine in Asia meant that populations crashed in the face of poaching outside and inside the protected areas.
Professor Nigel Leader-Williams, from the University of Cambridge's department of geography, who contributed to the study, said: "The long-term goal is to conserve an Asia-wide network of large landscapes where tigers can flourish.
"The immediate priority, however, must be to ensure that the few breeding populations still in existence can be protected and monitored.
"Without this, all other efforts are bound to fail."
The researchers said tigers were mostly restricted to small pockets in protected areas, with 42 places identified as "source sites" which contain breeding populations that have the potential to repopulate larger areas.
These sites contain the majority of the world's remaining tigers.
Protecting the tigers in these areas, with strong law enforcement, wildlife management and scientific monitoring, would lead to a rapid reverse in the decline of populations at a relatively low cost.
It is an approach that has worked well in protecting rhinos in Africa, the researchers said.
According to the study, efforts to protect the tiger at its source sites would cost just 35 million US dollars (£23 million) a year more than is currently being spent on tiger conservation.
India is the most important country for the key conservation sites, with 18 identified, while Sumatra has eight and the Russian Far East has six.
No sites have been identified in Cambodia, China, North Korea or Vietnam.
The paper is released ahead of a meeting in Russia in the autumn which brings together the 13 tiger range states, conservation groups and other countries in a bid to take major steps to save the tiger.
The study's co-author, John Robinson, from the Wildlife Conservation Society and overseas fellow at Churchill College, Cambridge, said: "The tiger is facing its last stand as a species.
"As dire as the situation is for tigers, conservationists know what it will take to save the tiger in the wild, and we are confident that the world community will come together to bring these iconic big cats back from the brink of extinction."