Data from the radio-collared tigers, as a part of a nationwide census, will enable acomparison between the observed behaviour of tigers from across the country with those living on the estuarine islands of the Sunderbans, officials said on Monday.

On Sunday, a radio-collar was fastened onto a male tiger before it its release into the wild. This is the first time a male tiger was being monitored, said field director of the Sunderban Tiger Reserve Subrat Mukherjee. “Normally the territory occupied by a male tiger is 15 sq km and that of a female 35 sq km. We wanted to see if the figures are the same for tigers here in Sunderbans.”

Director of the Sunderban Biosphere Reserve Pradeep Vyas said, “We hadn't radio-collared a male tiger before. But as per the project design of this census, we are going to monitor tigers of both sexes.”

The Sunderbans is the only mangrove region in the world known to be inhabited by tigers and it seems they have uniquely adapted to the environment. Besides being expert swimmers, the big cats in the Sunderbans are known to drink saline water and eat fishes, crabs, turtles and even snakes.

“However, there is no scientific data available yet to analyse how the Sunderbans tiger is different from the terrestrial tigers. The data from the DNA analysis and radio-collaring collected during this census should help us in this regard,” Mr. Vyas said.

Since February, collars were fastened on three tigresses and a tiger. But a radio-collar on one of the tigresses fell-off and it was found by officials on March 11.

It is planned that six “normal” tigers will be monitored as a part of the current census. But the reserve authorities will also monitor about four tigers with aberrant behaviour.

“We want to keep a watch on the incidents of tigers straying into villages,” Mr. Vyas said. Of the 102 islands in the Indian side of the Sunderbans, 54 are inhabited. Incidents of tiger attacks in the villages and man-animal conflict are reportedly on the rise. Since July 2009, the reserve authorities were inserting microchips into the tigers that stray into villages.

However, so far there was no instance in which a tiger that entered a village area was found to have been tagged with microchip, said Mr. Mukherjee.