The researchers use faux-bois (false wood) gadgets such as cameras and infrared motion sensors, etc.
These gadgets are placed at strategic locations after studying the tiger tracks and locations where they poop.
Tigers are known to be predictable when it comes to the trails they follow; so with data about tracks and poop, researchers can finalize locations to install cameras.
Once installed in each identified location, these cameras are checked every day to make sure they haven’t been knocked down by the animals.
Now, whenever the infrared sensor senses motion, it clicks a picture — this means pictures of other animals also get clicked.
After a number of pictures have been collected over the sampling period (a week or two), researchers remove the cameras and start sorting the pictures.
They discard pictures of other animals and examine the tiger images manually.
Since one tiger could trigger the camera several times, researchers can’t just count the total number of tiger photographs and declare that as the total tiger count.
So, they identify individual tigers from photographs using the tigers’ unique pattern of stripesEach tiger has a unique pattern of stripes, the way each human being has a unique pattern of fingerprints, and accordingly declare the count — this is called the first tiger count.
Then the second tiger count is done using the same method (cameras, infrared motion sensors, etc.).
To arrive at the estimated tiger population, the first tiger count is multiplied by the second count and this number is then divided by the total number of tigers that were common in both counts.
E.g. let’s say researchers found 40 tigers in the first count and 50 tigers in the second count, and 10 tigers were common in both these counts.
So, the estimated tiger population would be (40 x 50)/10 = 2000/10 = 200.
To achieve higher accuracy, multiple counts (and not just first and second counts) are done and computer programs are used to estimate the total numbers.
Before the camera method, researchers used spoor (paw prints, also called pugmarks, and poop), which often led to the same animal being counted multiple times.
Comparing data collected by old methods with that collected by new methods can lead to misleading figures (exaggerated decline).For example, if the old method(because it counted the same tiger multiple times) estimated the population to be 300 and the new method estimated the population to be 200, there is a decline of 33%. In reality, this could be just 10%.
