BDT-130,Caught on Camera

Every year,around October,a team of 10-15 CWS employees and a small army of trained volunteers embark on an intensive survey of Karnataka’s major tiger reserves – Nagarahole,Bandipur,Bhadra,Kudremukh,Biligiri Ranganathaswamy Temple and Anshi-Dandeli,not always in that order — and wind up just before the monsoon. The exercise involves setting up and monitoring hundreds of motion-and heat-sensing cameras on forest paths frequented by tigers (a method known as camera trapping that yields a scientific estimate of tiger populations) and counting prey species while walking along pre-marked routes.

At Hulikanu,as dark begins to shroud the cottage and the surrounding coffee plantations,the Jeeps return and tired researchers file in,leaving their field shoes and leech socks in the courtyard. As they sit down to eat in the relative safety of the field station,the cameras turn on in the wild,ready to surprise tigers with a flash and a click. Since tigers are nocturnal,the cameras are programmed to go into active mode at 6 pm and to switch off at 6 am,says Naveen Kumar,a researcher who has been with CWS for three years. “Every tiger has a different set of stripes by which it can be identified. We set up camera traps on either side of paths so that both flanks can be captured when a camera is triggered,” he says.

A reserve is typically camera-trapped for about 20-25 days every year,after which the data is analysed and published as an annual report. The Bhadra reserve,with its rolling hills and moist deciduous forests,is one of the most promising tiger sanctuaries in India,with animal density growing rapidly,says Ullas Karanth,founder-director of CWS,and a senior scientist with the Wildlife Conservation Society,New York.

A leading expert on tigers in India,Karanth has been monitoring their numbers in Karnataka for the past 20 years,in one of the longest continuous studies of tiger ecology in the world. Of the 14,000 sq km in the state occupied by tigers,his team camera-traps 3,000-4,000 sq km at a cost of about Rs 1 crore per year. “Tigers are wide-ranging carnivores,so in reserves like Bandipur and Nagarahole,their numbers have plateaued at 12-14 per 100 sq km. In Bhadra,there are just three-four tigers per 100 sq km,but with prey populations on the rise,I expect it to reach the same density as Nagarahole in another 10-15 years,” Karanth says.

India,home to more than half of the world’s tigers,started counting them in 1972,when their number — arrived at by counting pug marks,now considered unscientific — was 1,872. The first National Tiger Assessment in 2006-07 “sampled” tiger populations instead of a pug mark-based census. The 2010 National Tiger Assessment,the results of which were announced in March this year,has pegged India’s tiger population,spread across 39 reserves,at 1,706 — an increase over the 2006 estimate of 1,411. This figure,however,isn’t acceptable to many conservation experts,who have argued that the so-called growth in tiger numbers is due to the addition of new areas that were not sampled before.

According to the latest estimate,Karnataka,which holds about 15 per cent of the country’s tigers,now has 300 of them,beating Madhya Pradesh,which was home to the largest tiger population in the country according to the 2006 survey. According to CWS data,the tiger population in the state is stable at best,increasing only in reserves like Bhadra and Kudremukh. “Most of India’s source population (reproducing population that produces a surplus) of tigers is concentrated in 10 per cent of the tiger habitat. These 40-odd source populations,which have high birth and death rates,need to be monitored annually with intensive camera trapping instead of relying on a survey once in four years. If we see a fluctuation in populations,we can take immediate corrective measures,” says Karanth.

Earlier this year,based on these suggestions,the National Tiger Conservation Authority agreed to initiate “Phase IV” of the national tiger estimation exercise,under which double-sided cameras will be deployed at a density of 25 per 100 sq km in areas with critical tiger populations. For the first time,non-governmental organisations like CWS are likely to be made part of the effort. The key threats to high-density tiger populations,besides poaching,are shrinking habitat and hunting of prey. In 2006,tigers occupied 93,600 sq km of India’s forests; this area is down to 72,800 sq km.

The next morning,as the mist lifts over Hulikanu,researcher Kiran Yadav prepares for his daily tour of Block V,which encompasses private coffee plantations threaded with slender silver oak. Spread across 700 sq km,Bhadra has been divided into five blocks to enable simultaneous camera trapping of the entire area. A pair of researchers manually check every camera trap every day for the course of the survey. Block V has 17 pairs of traps,each encased in a rain and theft-proof metal box mounted on a pole set in the ground. Leaving the Gypsy by a culvert,we walk up a dirt path buzzing with giant flies to reach the first camera point on the route. Armed with an infra-red sensor at the centre,the cameras can be set to high sensitivity —10-12 metres — or standard sensitivity — 5-6 metres. Yadav notes the serial numbers of the cameras,the frames they shot last night,and the rolls of film. “In a spool of film,we typically get just one or two tiger frames,” says Samba Kumar,deputy director,conservation science,Wildlife Conservation Society – India Program and CWS. Last year,the survey in Bhadra yielded 370 rolls that were painstakingly processed to obtain 100-120 profiles of 14 individual tigers. The reason they don’t deploy digital cameras yet,Karanth says,is the lag in clicking pictures. CWS is working with Intel (Bangalore) to develop cheap but effective digital cameras.

Back at the CWS office in Bangalore,a small team is analysing data from surveys of the other reserves. They use the “capture recapture method”. “From counting the number of individual tigers based on their stripe patterns and by noting the frequency of their appearance in front of a camera,we estimate how many individuals we did not get on camera at all and thus,the total number of tigers in the reserve,” Samba Kumar says,pointing to tiger images that are being fed into a 3D modelling software.

With Phase IV commencing in November,India’s tigers are set to be monitored more closely in a scientific way. “Look at what happened in Sariska. Forest personnel reported pug marks even when there were no tigers left in the reserve. This is where annual monitoring by camera traps can help,” says Kumar. “When a male tiger named BDT-130,caught on camera at Lakkavalli,in Bhadra,in 2006,was photographed again in Anshi-Dandeli in 2009,it was a matter of surprise and awe,the tiger had travelled 200 km to another reserve,” says an excited Patil.

What is it about tiger conservation that prompts youngsters — most CWS researchers are in their 20s and early 30s — to forsake urban comforts and risk their lives? Tigers are the flagship species of deciduous forests and their numbers indicate the health of a habitat. But that’s not nearly reason enough. It’s the easy majesty of the animal,as it walks softly on its paws or rests on a bed of leaves,making you feel you are in the presence of royalty.