Uneven prey base behind straying: Officials
Krishnendu Bandyopadhyay & Monotosh Chakraborty, TNN, Jun 10, 2010, 04.40am IST
KOLKATA: In 2001, tiger straying in the Sunderbans broke all records with 26 incidents. In 2010, less than half a year gone by, the number has crossed the 26 mark. Last month, as many as five tigers raided several villages over just two days. The trigger, apparently, is Cyclone Aila.
Uneven distribution of prey base and depletion of the vegetation favoured by tigers are the biggest reasons behind straying in the Sunderbans, say experts. "Post-Aila disturbance is a crucial factor," the state's chief wild life warden S B Mondal said.
Analysis of recent radio-collar inputs says that the prey base has not dwindled. It is the uneven distribution that is leading tigers to drift in search of prey, say forest officials. The study, carried out Sundarbans Biosphere Reserve (SBR), also shows a steady decline in the tiger's favourite vegetation, the vanishing mangrove species of Hetal (phoenix paludosa).
On an average, 12 to 18 tigers stray in a year in the Sunderbans. "We first weed out the common factors a tiger strays if it is old and cannot hunt, if it's the mating season when the big cats look for easy prey, or of it's a tigress with cubs," said SBR director P K Vyas.
No other tiger habitat in the world, says Vyas, is impenetrable by cattle like cow and goat. In the Sunderbans, the only prey available to tiger are deer and wild boar. "There is no absence of prey, but there certainly is an imbalance in the distribution of prey base in the tiger-islands. In Dobanki, we got deer five years ago. The third generation deer were released in the forest after being completely acclimatised with the food and ecology of the mangroves. Since our first experience was a success, we want to replicate it on other islands too," said Vyas.
Senior forest officials suggest radical changes, like restricting tourism or shifting tourism hubs on the basis of new tiger zones. Animesh Sinha of Sundarbans Environment and Eco Development Society (SEEDS), who has been working in the islands for a long time, vouched that there has been a steady increase in the tiger population. "With this growth, each tiger now has a smaller territory. So straying is on the rise."
Wildlife expert Pranabesh Sanyal said: "Rivers and creeks in the sea facing islands have witnessed an alarming rise of salinity, specially after Aila. This is forcing tigers into the southern core area, with declining prey density in the northern zone."
Botanical Survey of India (BSI) officials feel global warming and increasing salinity of Sunderbans rivers is triggering a major change in the habitat vegetation of the mangroves. "We have studied the phenomenon. Now we will have an in-depth study how the vegetation is undergoing rapid changes in the Sunderbans, one of the most sensitive biodiversity zones in the world," said Dr H K Debnath, principal investigator of Lead Institute of BSI.