In order to save tigers from extinction, their preys need to be protected, say scientists.
 
Chris Carbone of the Institute of Zoology in London pulled together population data for 11 carnivores and examined how they were affected by changes in numbers of their prey.
 
Fewer prey always meant fewer predators, but for large carnivores the effect was five times as great, reports New Scientist.
 
"For large predators, it's more important to protect their prey," agreed Guillaume Chapron of the Grimso Wildlife Research Station in Sweden.
 
Ecologist Nick Isaac at the Centre for Ecology and Hydrology in Wallingford, UK, added that we need to know whether a lack of food is as big a threat as poaching.
In St Petersburg, money rather than food was pledged to save the species: the Wildlife Conservation Society promised $5 million a year, while actor Leonardo DiCaprio pledged $1 million.