How India counts its tigers7 min read . Updated: 01 Mar 2018, 08:27 AM IST
The National Tiger Conservation Authority is conducting the fourth assessment of the tiger population in India's 50 tiger reserves spread across 18 states. Here's a look at what the process involves
Pench tiger reserve, Madhya Pradesh: The dark grey lump on the forest floor got us into a small huddle. “It’s tiger scat," said the forest guard leading the trail deep inside the Pench tiger reserve in Madhya Pradesh (MP).
On foot patrol, forest guards are used to tracking animals by their scat—or droppings—every day. They hold vital clues on wildlife presence and population trends to biologists, conservationists and park managers.
So, in February, when I signed up as a volunteer in the All India Tiger Estimation 2018 that is underway, the documentation of scats was a vital part of the survey mechanism prescribed by the National Tiger Conservation Authority (NTCA).
The NTCA is conducting the fourth assessment of India’s tiger population (after 2006, 2010 and 2014) in four phases this year. I joined in the first phase, which recorded carnivore tracks and signs, data sampling of prey species, vegetation and human disturbance. Phase 2 consists of remote sensing data by the Wildlife Institute of India (WII), which partners the NTCA in this assessment every four years in collaboration with state forest departments. Phase 3 is when biologists from WII visit the tiger reserves and do a cross-check on the data collected in phase 1 as well as look at images taken by camera traps. In the case of tigers, every individual tiger will have a unique stripe pattern— just like our fingerprints. In the previous assessment—in 2014—1,686 different tigers were found by this method. Where the camera trappings are unavailable because of logistical constraints, DNA extracts from scat samples are collected for analysis.
In the last phase, all of this data, gathered from the country’s 50 tiger reserves that are spread across 18 states, is fed into computers with a specially designed software in order to generate information about density and population range. This information, expected to be available in the first quarter of 2019, will be the basis for the 2018 tiger estimation.
In 2014, the number of tigers in India was estimated at 2,226, a mean value from a range of 1,945-2,491 occupying an area of 89,164 sq. km.
Fieldwork and scat analysis are fundamental to the process of documentation; for starters, it’s important to know whether it’s a tiger or a leopard or some other animal. As the beat guard gave us a crash course on poop design—explaining how each species has its own unique size and design—we could finally tell leopard scat from the tiger’s (the former’s is smaller, knotty with a hook at the end). There’s more: whether it was a steaming fresh pile or a weathered sample was always the moot point of the huddle. The survey form demanded that we write down VF for very fresh, F (fresh), O (old), or VO (very old) along with the GPS coordinate. And that’s harder than it sounds. We stumbled upon a dark grey lump that was weathered and disintegrating. One of us prodded it with a twig. Was it just old—or VO? In this case, the field director of the tiger reserve, Subhoranjan Sen helped us make up our mind. We went with O.
Every morning, at the break of dawn, I accompanied Sen and his staff on their trails, which used to take us deep inside prime tiger territory. Walking in tiger country is always exhilarating, an adrenaline-charged hike where one also stumbles on the many secrets which lie on the forest floor. Every sound makes the heart beat faster in constant anticipation of something lurking around the bush or on the next bend.
We saw a small bush frog caught in a funnel-web spider’s web on leaf litter and how porcupines had stripped the bark off of the bottom of the tree trunks. There were assorted footprints—old and new—of birds and reptiles and of big cats, wild dogs and bears. Up in the trees, the greater racket-tailed drongo often fooled us by mimicking other birds while grey langurs whooped out false alarm calls for a lurking predator. Equally, blood-sucking ticks slipped into our clothes with ease.
The dry leaves exploded under our feet as we scoured the forest. There were other signs, too. The first three days were strictly for carnivores. In Pench—the famed setting of Rudyard Kipling’s The Jungle Book—one gets to spot tigers, leopards, wild dogs, wolves and jungle cats. Although we couldn’t spot any, there were tracks and other signs aplenty. Signs we had to track and document ranged from pugmarks, claw marks on tree trunks, urine spray (big cats mark territories by repeatedly spraying urine on forest trails), animals rolling on the grass, digging, the leftover of kills and any vocalization.
For three consecutive days, every morning we went searching. The rocky outcrop and the ghost trees of Pench painted a picturesque terrain as we walked up and down the undulating landscape. There were plenty of herbivores and birds but the big cats, wild dogs and bears gave us the slip. But one day, as we huddled over a track sign, we heard a tiger call from a nearby hillock—barely 30-40m away. After gathering our wits, by the time we managed to climb the rocks, the animal seemed to have vanished into thin air.
According to the last nationwide count in 2014, there are likely to be about 43 tigers (from a range 35-49) in Pench, which has one of the largest prey bases among all tiger reserves.
According to the NTCA’s mandate, we had to cover at least 15km in three days and every track-sign record was to be supplemented by information on GPS points. An area under a tiger reserve is divided into several ranges. The range area is divided into smaller “beats". In Pench, MP, (a part of Pench is also in Maharashtra) alone there are 109 beats and around 250 staff involved in the estimation work.
Part two of the phase I estimation required us to do “transect walks"—these involve walking along a straight line of minimum 2km, drawn across the forest with the help of GPS and marked by painted dots on tree trunks.
Here, using a rangefinder and compass, the field staff gathered data on prey species—herbivores such as deer and antelopes —for the next three days. Whenever a group of herbivores was spotted left or right of the transect line, it was noted down. Further on the return walk, pellet densities (herbivore poop), vegetation data and human disturbance, if any, were recorded.
Technology isn’t always a magic bullet in the forest. NTCA has also created a mobile app, M-STrIPES (Monitoring System For Tigers-Intensive Protection and Ecological Status) to make data gathering easier and more transparent. But although it was put to use in the field, the app’s GPS readings did not match those of the handheld GPS units. Also, most of the forest guards still use basic phones or are unaccustomed to smartphones. So, the age-old practice of filling forms continues.
While we were on the trail, phase 3 of the estimation process was also going on in tandem. Camera traps placed at strategic points on a 1.4 X 1.4 sq. km grid (covering a 2 sq. km area) were recording all animal movements. To give a sense of the scale, around 360 pairs of camera traps were set at one go over 25 days before being moved around the park.
“Coordinating the movement of equipment and ensuring proper training to field staff have been challenging in this on-going estimation," said Sen.
MP and the central India landscape has been always an important area for tigers. For logistical reasons, the state has demarcated its tiger bearing areas into seven zones. “This is the largest wildlife survey anywhere in the world. We have over 14,000 camera traps to cover over 30,000 beats, an area over 5 lakh sq. km across the six tiger landscapes in 18 states," says Sanjay Kumar Pathak, deputy inspector general, NTCA. The six tiger landscapes are the Shivalik Hills and Gangetic Plains; central India; the Eastern Ghats; the Western Ghats; the North-eastern Hills and Brahmaputra Floodplains; and the Sunderbans. The cost of this exercise is estimated around Rs10 crore.
According to NTCA, except from Sunderbans in West Bengal, all field data are to come in by August-September and by the end of the first quarter of 2019, the ministry will publish the final results. Though some critics have questioned the methodology, the tiger population in India has been seen to grow by 5.8% annually. In 2006, there were 1,411 tigers, 1,706 in 2011 and 2,226 in 2014. With many new cubs reported from the tiger tourism circuits, the numbers are likely to rise.