Bisons cross a forest path in Jaldapara Wildlife Sanctuary. File picture
A food chain problem of plenty and scarcity dogs the Indian bison in the forests of north Bengal.
Plenty because they have flourished in the near absence of tigers. But the herbivores now hardly find enough grass to keep themselves fed in the forests. Inevitably, the animals have strayed into human habitat and several of them have got killed.
The food chain imbalance — not enough tigers to eat bison — has led to the doubling of the number of the herbivore.
Forest department sources said that according to the 2010 census, the population of the Indian bison (gaur) in all the reserves of north Bengal was nearly 2,000. In 2012, the number rose to 4,000.
In comparison, the number of tigers in north Bengal is less than 30.
“In the forests of north Bengal the population of tiger is low. As the tiger is at the top of the animal food chain and consumes herbivores, its near absence in the forests has led to the flourishing population of the gaurs,” an official said.
According to forest department data, the Buxa Tiger Reserve and Jaldapara forest have some tigers but the bison population is concentrated mostly in Gorumara National Park and Chapramari wildlife sanctuary in the Dooars where there are no tigers anymore.
“In the 2010 census, there were around 2,000 gaurs in north Bengal. The population now stands at around 4,000. Although there are leopards in the forests of north Bengal, the animals can’t kill gaurs. Leopards may attack the calves, not the adult bison,” the forest department official said.
But the grass in the forests cannot sustain the Indian bison. The forest department does not have enough funds to plant more grass.
“We could not plant grasses and plants in the stretches of grasslands within the reserve forests of north Bengal because of lack of funds,” a senior forester said.
“As a result, the gaurs come out of the forests and enter neighbouring villages. There are instances where the animals have killed and injured people and have suffered injuries too,” said a senior forest official.
The data available with the forest department shows that in the past two years, 11 gaurs sneaked into human habitat close to forests and seven of them were killed.
Last month, two such incidents were reported in Alipurduar and Dhupguri.
In January, a bison strayed out of Chilapata forest and entered a village in Alipurduar-I block. The animal injured three persons before retreating into the forest.
| Bisons in the Gorumara National Park. File picture
Last year, two bisons were mowed down by speeding trains in separate incidents in the Dooars.
“The shortage of fodder is making the animals stray into villages,” said Sujit Kumar Das of Nature and Adventure, a wildlife NGO in Odlabari.
Vipan Kumar Sood, the conservator of forests (wildlife, north Bengal), said: “The state government has taken some initiatives to plant grass. However, the principal funds come from the Centre and we are yet to get the money for the current year.”
Foresters said bisons have weak hearts and often die when chased or darted.
“If a bison is chased or tranquillised, it dies as the animal has a weak heart. Although our employees take a lot of care while darting or guiding an animal back into the forest, such deaths can occur. There are also instances when gaurs were killed by villagers after the animals injured people,” said a senior forester.