Kolkata: Scientists of the Wildlife Institute of India (WII) reveal that Sunderbans tiger population has almost reached its carrying capacity.
Carrying capacity of populations is the maximum number of individuals that can live in a population securely. According to scientists of WII, who are compiling data as part of the All- India tiger census, this can be a worrying factor if movement corridors are disturbed. Moreover this would lead to over-crowding of tigers, compelling them to enter human zones of habitation.
Movement of tigers across the Sunderbans of India and Bangladesh are very important to distribute tigers from high densities to low densities thereby minimizing their need to venture outside the mangrove forests into human habitation.
“Since 2010, when the population estimation of the swamp tigers was done for the first time using scientific methods, there is not much change in the big cats’ density in the mangroves. In 2010, the Sunderbans Tiger Reserve (STR) threw up a density of 4.3 big cats per 100 square kilometres which meant there were 64 to 90 tigers in the mangroves. Based on data available so far, the density of tigers this year is so far hovering around 4 per 100 square kilometres. It points to the fact that the population is either very close to the carrying capacity of the forest or has already reached it,” said Y V Jhala, senior scientist with WII to a leading newspaper.
“The trend on prey population that we are getting from the tiger reserve area at the moment — 8-11 deer per square kilometre or around 25,000 across the reserve — can at the most sustain a healthy population of about a 100 tigers,” said Jhala, adding that it’s natural as every forest can support ungulates up to a certain limit. “In Kanha, there are 50 deer per square kilometre. The nature of the mangroves forest is such that it is good for the marine system and not for the terrestrial one,” he said.
According to another scientist of the WII, Qamar Qureshi, the forests outside the reserve area should be protected now. “Because, the young tigers will start moving out. There should also be a joint mechanism by India and Bangladesh to track the movement of tigers between the Sunderbans of both the countries,” he added.
Wildlife biologist Vidya Athreya said this was an exciting finding. “Carrying capacity of tigers in a forest mainly depends on the prey population. Keeping aside factors like poaching and calamities, a certain number of prey species can only sustain a certain number of tigers. If the tiger number reaches that limit, one can say that the big cat population has reached the forest’s carrying capacity, which means the forest can’t support tigers beyond this,” said Athreya.
According to her, the population should be monitored properly in the days ahead to find out whether it’s showing any decreasing trend or new tigers are coming in from other population.