Krishnendu Bandyopadhyay | TNN | Mar 28, 2017, KOLKATA: A never-before experiment in Bengal — to reintroduce tigers in a forest that has not reported a steady sighting of the big cat for nearly three decades — has raised questions about the pitfalls of tinkering with nature. The National Tiger Conservation Authority, a wing of the Union ministry of environment and forests, and the state have decided to relocate at least six Bengal tigers from Assam to the Buxa tiger reserve (BTR) in north Bengal. But Buxa has not had an officially recognised tiger sighting since the early 1990s and this vacuum has been filled up by a host of smaller predators, like leopards, clouded leopards and wild dogs.
Experts now wonder whether this forest has the prey base to accommodate both "the dogs" (the old occupants) and "the cats" (the new occupants) and what impact this may have on the forest and its inhabitants.
A recent camera-trap study on lesser cats in four key ranges of Buxa managed to capture only one image of spotted deer — a favourite prey of not only tigers but also wild dogs and leopards, population of which has grown inside the park. A melanistic leopard — probably the first photo evidence of the animal in Buxa — and a clouded leopard were clicked in the forest last year as were images of endangered wild dogs and a large Indian civet cat.
"From the foothills to dense vegetation, cameras have captured images of wild dogs at several locations. Low density of tigers seems to have paved way for population growth of these small predators. This also points to a good prey base," said Buxa field director Ujjal Ghosh. But, experts are worried if the existing prey base can sustain both the relocated tigers and the small predators in Buxa, where large-scale cattle grazing — more than a lakh cattleheads enter the forest every year — has led to loss of habitat like grasslands in the park.
Asked if the 'absence' of tigers can lead to population growth of small predators, conservation scientist Ullas Karanth said, "It's possible, particularly in case of wild dogs (dholes) and leopards which hunt some of the same prey as the tiger." But, he feels mere sighting of predators or "presence data" do not indicate high prey densities.
Ajanta Dey of NGO NEWS, which had done a study on lesser cats in the park, is upbeat. "Forests in Jayanti, Gadadhar, Newlands and Phanskhawa have good prey density with herbivores like Himalayan serow, goral, hog deer, barking deer and spotted deer. Grasslands have been developed in Nimati and Hatipota too. If the officials manage to address the problem of cattle grazing inside the reserve, I believe the tiger relocation plan will succeed in the long run," she said. A prey-base estimation was undertaken in Buxa recently.
Though a recent study by Wildlife Conservation Society in forests of South India revealed that tigers, wild dogs and leopards have developed smart adaptations to coexist, Padma Shri Ullas Karanth has a word of caution. "My research shows that a prey base of 500 medium and large-sized ungulates is needed to support a single wild tiger. Therefore, I think the first step should be to conduct research to estimate prey densities to know how many tigers can be supported in the park now and how many in future. This basic research has not been done in Buxa, I think. Introducing tigers without adequate prey base, a small area, and proximity to high-density human settlements may lead to serious conflict in future. Of the dozens of attempts to introduce tigers over the years, only one in Panna has fully succeeded. All others have failed, sometimes with tragic consequences for tigers as well as for local people," said the WCS director for science in Asia.
"Conservation efforts will be even harder if local people turn hostile to tigers. It is likely that these introduced tigers will range widely initially, and given the small size of Buxa (750 sqkm) and high human density around it, there is a high probability of human-tiger conflicts. I am not sure this is a wise decision, if it it is true at all," Karanth signed off.