The first phase of the tiger census, which included collection of signage and direct sightings of the big cats, in the Sunderbans was completed on Tuesday, although officials said that it would probably take a year to obtain estimates of the population.

“The first phase that began on March 4 went off smoothly and has shown some positive signs as there were a number of direct sightings,” Pradeep Vyas, director of the Sunderban Biosphere Reserve said.

“I personally observed three tigers during the field study,” said Raju Das, joint-director of the reserve.

The data collected by the 35 teams on the field is yet to be collated. It will take about two months to process the data collected after which it will be sent to the Wildlife Institute of India (WII) where it will be analysed. The third phase of the project involves the setting up of camera traps and radio-collars, Mr. Vayas said.

The process of fitting radio-collars, although is a part of the third phase, has simultaneously been initiated and two tigers have already been tagged, Subrata Mukherjee, field director of Sunderban Tiger Reserve said. Overall, radio collars will be fitted to about 7 tigers.

In conducting the first phase of the census, which is a part of a nationwide exercise to estimate the tiger population, the terrain posed the greatest challenge.

“Collecting pugmarks or scat in the Sunderbans is particularly difficult as in several parts they are washed away every 12 hours in the cycle of low tides and high tides,” Mr. Das said. Logistics, arranging for boats and walking in places with knee-deep water were other obstacles for officials and volunteers.

The terrain and a shortage of staff is posing to be a challenge in the ongoing survey at the Buxa Tiger Reserve as well.

“Conducting the survey, especially in the hilly areas is proving to be a challenge. However, the help of volunteers from various NGOs is making up for it,” said R. P. Saini, field director of the Buxa Tiger Reserve.

“This also brings in transparency into the process,” Mr. Saini added.

One of the problems was also to adapt the statistical model which has been developed at the national level on ground, said Animesh Bose of the Himalayan Nature and Adventure Foundation that provided trained mountaineers as volunteers.

“For example, the guidelines for a transect of four kilometres cannot be achieved in a hilly area at all and we had to break it down into shorter stretches,” he said.