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KOLKATA: Indian Sunderbans is set to post a handsome growth in tiger numbers in the national report likely to be released next month.

If the initial trend in the analysis made by the state forest department is to be believed, at least 94 big cats were photographed in the mangroves, including the tiger reserve and the South 24 Parganas forest division areas, during the camera-trap exercise for 2018. The count was 87 in 2016-17.

State foresters are yet to go official about the number because the final data, to be compiled by Dehradun-based Wildlife Institute of India (WII), will be arrived at after using refined technology that will eliminate possibilities of the same animals being counted twice.

A senior state forest department official said they expected an upper limit of 110 tigers on the Indian side of the Sunderbans. "Ninety-four unique frames mean the mangroves are home to at least 94 tigers. We fed the data in a software called Program MARK that can provide population estimation of marked animals. It indicated an upper limit of 110 big cats in the Sunderbans," the official added.

According to the official, 64 big cats were photographed in the tiger reserve area and 30 others in the buffer zone. During the same exercise in 2016-17, the figures stood at 62 in the tiger reserve and 25 in the buffer zone. The National Tiger Conservation Authority (NTCA) is expecting to release the all-India tiger estimation report, including the Sunderbans' data, in the first week of June, its member secretary Anup Nayak said. "We are trying to incorporate data from the Bangladesh Sunderbans as well," he added.

A senior Bengal forester said they would wait for the WII report to be released by the Centre shortly.

"They will use mark-recapture sampling for a reliable estimation," he said. In the mark-recapture or capture-recapture method, an initial sample is obtained and marked first. A second sample is then obtained to detect how many animals were marked earlier, eliminating the possibility of an overestimation.

