India is starting a comprehensive census of its Bengal tiger population in an effort to discover why the number of animals is declining.

Officials are focusing on national parks and reserves in developing, for the first time, a central database of photographs and other information concerning the nation's tigers to help monitor their numbers.

Officials told the BBC there are approximately 3,500 tigers in India today, compared with 40,000 a century ago.

The first stage of the survey involves checking the health of tiger habitats across 17 Indian states.

Copyright 2006 by United Press International