The unique challenges posed by the terrain of the world’s only mangrove tiger habitat prevented the use of a software-based tool to count their numbers for over a decade.
After modifications, the system is finally fit for use in the Sunderbans in the upcoming national tiger census, said wildlife biologists and foresters at the helm of the project.
MSTrIPES (Monitoring System for Tigers: Intensive Protection and Ecological Status), launched in India in 2010-11, has been widely used across tiger reserves in the country and for the 2018 tiger census. “MSTrIPES is a robust system. But it was suited for a land-based survey. Unlike any other tiger habitat in India, the rivers and creeks are an inseparable part of the Sunderbans. Adapting the software to the mangrove terrain took time,” said a retired forest official who has served in Bengal for decades.
The installation of cameras to click the tigers, the most important part of the census, is scheduled to start in the Sunderbans from Sunday. In the coming weeks, foresters will trudge through the four ranges of the Sunderban Tiger Reserve, deploying 1,200 cameras at strategic points.
“We will have 10 teams which will install the all-weather night-vision cameras across the four ranges. The cameras will be retrieved after 36 days and the data fed to a central server. The same cameras will then be used in the South 24-Parganas forest division,” said Tapas Das, field director of the tiger reserve.
Animal movements activate the sensors in the cameras, which then take photographs.
The Sunderbans is spread across 10,000 sqkm, a little above 4,000 sqkm of which is in India. The Indian Sunderbans is split between the tiger reserve and the South 24-Parganas division.
The Sunderbans Tiger Reserve, spread across 2,500 sqkm, comprises the Sunderbans National Park (East and West) marked as the core area, and the Sajnekhali Wildlife Sanctuary and the Basirhat Range, which form the buffer zones.
The tiger census involves three components — reconnaissance survey, herbivore survey and the camera trapping exercise.
The recon survey involves a study of anecdotal and tourist records of tiger sightings, pugmarks and other signs. “The recon survey is an ongoing exercise. The herbivore count will start from December 18,” said Das.
The herbivore or prey base estimation, a vital cog in the big cat count, is done from patrol boats in the Sunderbans.
Researchers at the Wildlife Institute of India, which is collaborating with the National Tiger Conservation Authority and state forest departments in the census, said the MSTrIPES needed several modifications to be fit for data collection from the boats.
“In the Sunderbans, we have to factor in the tidal timings which changes visibility. The modifications to MSTrIPES took time. But it is ready for the Sunderbans now,” said Yadvendradev Jhala, a senior scientist at the Dehradun-based Wildlife Institute of India.
The 2018 census had pegged the number of big cats in the Sunderbans at 88.