In a major step towards conservation of tigers, the government has decided to conduct a programme to monitor the wild cats annually instead of every four-year cycle.

The programme, Phase IV of the All India Tiger Estimation exercise, is a process of intensive, annual monitoring of important "source" populations of the wild cats.

Through 'Phase IV' of the exercise, annual monitoring of tigers at the tiger reserve level will be held across 41 protected areas.

"This marks an important milestone in our comprehensive tiger conservation strategy," environment minister Jairam Ramesh said in a statement in New Delhi.

"Annual monitoring, (instead of only a four-year cycle) at the tiger reserve level will allow us to get regular updates on the number and health of tiger populations across the country, and will strengthen our tiger conservation efforts," he said.

The programme will commence from November this year. The decision to begin Phase IV monitoring was made at a workshop on 'Best Management Practices in Tiger Conservation', held from May 9 to 11.

The methodology for monitoring the "source" population of tigers will be developed by the Wildlife Institute of India (WII) and the National Tiger Conservation Authority (NTCA), in consultation with experts. It will use statistically sound procedures to estimate numbers of both tigers and their prey.

The tiger monitoring protocol will use camera traps, at a density of 25 double-sided cameras per 100 square kilometres, and a minimum trapping effort of 1000 trap nights per 100 square kilometres, the ministry said.

"This will provide a yearly indication of the status of critical tiger populations around the country, and will be critical to long-term management and conservation of tiger populations," it said.

Prey population monitoring will be conducted simultaneously, using distance sampling protocols.

"Distance sampling will be conducted along line transects already established in phase I, and will use a minimum of 30 spatial replicates for 2 km each, and a total effort of 300 km," the ministry said.

60 per cent of the world's wild tiger population is found in India.

Across a system of 41 tiger reserves, the 2010 National Tiger Assessment estimates that there are 1,706 tigers (range between 1571 and 1875).

This is an improvement from the 2006 estimates of 1,411 tigers (range between 1165 and 1657).