NEW DELHI: Tigers need much more space than our protected areas or tiger reserves provide for currently. While that's true for all wildlife, a recent study published this month in Biological Conservation journal has highlighted how lack of space could be linked to a fast disappearance of tigers from certain habitats, particularly tropical dry forest areas. Sariska and Panna tiger reserves, both tropical dry forests experienced complete extinction of tigers in 2004 and 2009; the study explains what may have led to their complete disappearance.
Some tigers have been re-introduced in Panna and Sariska.
The study documents the space requirements of tigers in Panna tiger reserve before the extinction of tigers only to find a major mismatch in scale of their ranges and the sanctuary size, which exposes tigers to various anthropogenic threats including poaching and retaliatory killings outside the boundary. The reason for such large home ranges of tigers in tropical dry forests is still being studied, authors said but could be linked to ecological factors like prey population, water or shade.
The study involved field studies between 1996 and 2005 that monitored tiger movement through radio telemetry and direct sightings in the 543 sqkm area of Panna. Annual home ranges of both male and female tigers were estimated and then overlaid on the sanctuary area boundary revealing how home ranges often breached the sanctuary boundary. According to the authors, this is the first comprehensive study of tiger home ranges in a tropical dry forest area and one of the longest studies on tiger in the sub-continent. The study documented detailed information on six radio-collared tigers over a period of nine years. While conducting the nine-year observations, the team also found some intriguing features. For instance, "Male tiger territories were not exclusive as generally believed. Instead, it was observed that females mated with several males in addition to the territorial tiger. But the role of these non-territorial males can be important but little is known about these tigers," said Raghu Singh Chundawat, lead author of the study.
The team concluded that home range of breeding or nursing tigers extended beyond the boundary of the sanctuary.
In fact what happened in Panna and Sariska are a part of a larger trend, researchers warned. The largest tiger habitat in India is in tropical dry forest category. But the probability of survival of tigers in these areas is much lower than in other habitats like tropical moist forests, alluvial grasslands or mangroves. Interestingly, more than 85% of the sanctuaries located in tropical dry forests are way smaller than Panna and have either lost the tigers already or sit with high risk of tiger extinction.
"The bottom line is that tigers need more space, and one may need to think out of the box, if tigers are to have a future in the already stressed landscapes," said Koustubh Sharma, co-author of the study.
The study recommends that a straight forward solution to the problem will be to protect larger forest areas but that's a difficult proposition in human dominated areas. "Small patches embedded in large landscapes can be conserved as a series of stepping stones to interconnect populations," the study said.
