The Telegraph
Monday , February 10 , 2014
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Thrice grow tigers in three years

- Camera trap enumeration helps VTR achieve perfection, experts differ

Patna, Feb. 9: The tiger growth graph is northbound again, after 21 long years.

In the past three years, the growth has been phenomenal at Valmiki Tiger Reserve (VTR) — from eight in 2010 to 22 in 2013. Chief minister Nitish Kumar, while releasing a report on the tiger census done by the state environment and forest department in 2013 yesterday, specified the number of big cats at the reserve, one-of-its-kind park in the state.

National Tiger Conservation Authority (NTCA) conducted the survey in 2010.

A senior official at the VTR said six more tigers, including three cubs, have recently been spotted at the reserve. “Three tigresses have been recently spotted frequently at Manguraha moving with three cubs. These six tigers were not documented during the last census, thus the number of big cats at the reserve is expected to be 28 now,” said Santosh Tiwari, conservator-cum-director, VTR.

While the tiger reserve officials have attributed the surge in the number to improved administration and development of favourable habitat, some experts claim that the 2010 census was done in a faulty way due to which very few tigers were documented then.

“The 2010 initiative was part of the NTCA’s quadrennial (once in four years) census across all tiger reserves in the country. The NTCA census is based on tiger count in a sample area. Similarly, the sample area in the 2010 census was spread over around 400sqkm in the VTR’s core area. The number of tigers documented from the sample area was not extrapolated and it is due to this reason that the corresponding report had mentioned that there could be more tigers in the reserve. Thus, in my personal opinion, the actual growth in the number of tigers should not be thrice as being perceived from the findings of the latest census,” said Samir Sinha, manager of Wildlife Trust of India (WTI), who is researching at the VTR since 2003.

The tiger count at the VTR started from January 15, 2013, using 210 camera traps, which were installed in pairs over an area of 899sqkm in the reserve for collecting data. The census went on for the next six months and the findings were sent to Wildlife Institute of India (WII), Dehradun, for vetting the figures. Going by the figures stated in the final report, it is also the first time in the VTR’s history since 1992 that the tiger count has witnessed a surge.

The 2013 census was also the first such annual exercise done by the VTR mandated by the NTCA. According to sources, the NTCA, after consultation with tiger reserves of the country, introduced the system of annual census by tiger reserves themselves in November 2011. This process was introduced for keeping better estimates about the number of big cats on a regular basis.

The quadrennial tiger census by the NTCA was divided in three stages. The first is documentation of overall habitat at the reserve, the second is Geographic Information System (GIS) mapping by the WII and the third is counting through camera trapping in a sample area by an expert. The findings of the sample area are required to be extrapolated for coming up with final figures. The census by the reserve authority is the fourth step of the same exercise, where the tiger count is done by installing camera trap all across the reserve.

The VTR, 289km north of Patna at the Terai region of the Himalayas, extends to Royal Chitwan National Park and Parsa Wildlife Sanctuary of Nepal on its north and Uttar Pradesh on its west.

As the VTR shares boundaries with the Chitwan reserve of Nepal, the WII, which has a detailed report of Chitwan tigers with it, matched the VTR pictures with that of Chitwan to rule out duplication while counting the tigers. Camera trap is done for 30 to 45 days and based on the time of stay of a tiger in a particular park, the experts decide in which reserve a tiger should be counted. This is decided on the basis of maximum time a tiger is spending in a reserve.