Counting the tigers

What the tiger count all about?

The Royal Bengal Tiger is India’s national animal. Once, this majestic cat roamed India’s wide jungles. But as cities grew bigger and jungles smaller, the tiger got boxed into 50 tiger reserves in 18 states across the country. Some years ago, there was panic as the number of tigers had fallen to just 1411 individuals in 2006. Since then, a lot of attention has been given to the counting of tigers in India.

The last count was done in 2014 when 2226 tigers were counted. The next one is already underway and will be completed in 2018. When the results come out, everyone will be interested in the final number that emerges, but it is also important to understand the process (step-by-step method) that is being used to count India’s tigers. It will give you an idea of how nature can be ‘read’ and understand the wild at a different level. And of course, if you plan to work in the area of wildlife area, such understanding is very important.

Did you know?

The counting is being managed by the National Tiger Conservation Authority (NCTA) with help from the Wildlife Institute of India (WII).

Reading the signs

In the first stage people working in the tiger reserves, along with volunteers, are fanning out across the parks to track signs left by the big cats. These include scat (that’s droppings/dung), pug marks (imprint of the paw), urine sprayed by the animals (tigers mark territory by peeing on tree trunks and forest paths-it’s a sign to rival tigers to keep off!), claw marks on trees, sounds made by the cats and of course signs of kills made by a tiger. In addition to tigers, the NCTA is also capturing information on other carnivores (meat-eaters) such as leopards and bears.

Each time, any of the above is noticed, the details have to be recorded and the GPS co-ordinates have to be noted. GPS co-ordinates are found using satellites orbiting Earth in space and they are a set of numbers that point to the precise location of a point on the planet.

 Gathering data during the tiger count (Photo courtesy: Ananda Banerjee)
Gathering data during the tiger count (Photo courtesy: Ananda Banerjee)

The story about scat

Animal droppings are a great way for people to track the presence of animals. Each species generates its own unique form of poop-tiger scat for instance is very different from leopard droppings which are smaller and have a hook at the end. Tiger scat is a pile of log shaped poop. Trackers must also note how fresh the dung is as it gives clues to the big cat’s movements.

Tiger scat-the pen is placed there to give you an idea of size
Tiger scat-the pen is placed there to give you an idea of size

 

Walking the transect

Once they’ve tracked the signs of the carnivores or predators, tracking teams move on to track the herbivores (grass-eaters) that form the prey for the big cats. After all, the number of tigers that can survive in an area will depend on the amount of food available to them. That’s why it is important to get an idea of the prey base before the population of the big cats can be estimated.

A transect is a straight line that cuts across the nature reserve, along which observations are made. In forests, the transect is marked though painted dots on tree trunks and field staff walk along the transect line, making a note of deer, antelopes and other herbivores spotted on the left or right of the transect line. Multiple transects are drawn so that entire reserve is covered.

The presence of a good prey base is needed for tigers to flourish
The presence of a good prey base is needed for tigers to flourish

Capturing the cat

Not in a cage, but on camera-that is what the next stage of the tiger count involves. Camera traps are cameras fixed to trees that are programmed to take a snap when there is movement in front of the lens. Right this moment, hundreds of camera traps are being rotated across the tiger reserves to capture pictures of as many tigers as possible. Individual tigers can be identified by studying the pattern of their stripes-each tiger has a stripe pattern that is as unique as human finger prints.

Later in the year biologists from WII will be visiting the tiger reserves to cross check the data collected by trackers in the first phase. They will also study the camera trap images.

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Above images captured from the camera trap (Camera trap images from Pench Tiger Reserve)
Above images captured from the camera trap (Camera trap images from Pench Tiger Reserve)

So how will the final number be arrived at?

Data from the field surveys as well as camera trap images will be combined with remote sensing data collected by the WII (see below).All this data is then entered into computers running a special software that calculates population and spread of tigers in an area.  The last time, the count was done in 2014, the number of tigers in India was estimated at 2226 which occupied an area of 89,164 square kilometres. You must remember that the number 2226 is an average or mean value calculated from the low to high range of 1,945-2,491 tigers that the software came up with. This means that it estimated that there were at least 1945 tigers in the country with the largest possible number set at 2491.

What’s remote sensing?

Remote sensing satellites high up in space scan the Earth and take images of it. The images collected by them give us information about the physical features of an area-such as the kind of hills, mountains and water bodies found. This information is used to look at the quality and condition of a tiger habitat and mark new areas where tiger presence has been recently discovered.

An example of a remote sending image (Image courtesy: NOAA)
An example of a remote sending image (Image courtesy: NOAA)

 Walking the talk

Ananda Banerjee is a Delhi based wildlife author and photographer. In February he was a volunteer during the tiger count at Pench National Park in Madhya Pradesh. We asked him about his experiences.

Q: How many days did you spend at Pench and what did you do there?

One week. Day one was a workshop for all volunteers to learn the estimation process, what to look for and how to record data. After the workshop volunteers were assigned to different forest chowkis or camps to cover respective beats. We then did the carnivore and herbivore surveys over the next six days along with forest guards.

Q: How will your work be used in the tiger count?

Our data collection covered the first four indices (plural for index which means measure)-Carnivore sign index, Prey abundance index, Habitat indices and Human disturbance. This is the first stage of the estimation process.

Q: What did you learn from your experiences?

This fieldwork gave me insights on how to read a forest even when one doesn’t get to sight animals. No book or research paper can provide this knowledge.

Q: What was the most exciting moment of the visit?

While we were on a trail, a tiger called from a hillock we were going around. That moment we all froze for a second and later when we gathered out wits and climbed the hillock the big cat had moved away without a trace.