There are many questions asked about the efficacy of the various methods of performing the tiger census. This blog posts focuses on the methods of performing the census and the merits of each.
The age-old and method of counting the number of tigers in the wild which was followed is the pug-mark method. Each tiger has a unique set of footprints. Thousands of forest personnel were expected to fan out across the forests and take measurements / create casts of the paw-prints of the left hind leg of tigers. The method is the cheapest but has various lacunas. It is difficult for the forest officials to traverse all parts of a forest in the interior areas missing out on counting of some tigers. It is even more difficult to chance upon all 4-pug marks of the tigers (the imprints would depend on the soil and the terrain as well). In the absence of all 4-pug marks, imprints of different paws of the same tiger could be mistaken for different tigers. The skills of the person lifting and measuring the paw prints would also be crucial in determining the uniqueness of the same.
The poop method (or scat method as it is also referred to) has the forest officers fanning the forests to collect the tiger feaces for DNA matching and sampling to identify different tigers. The positive of this method is that it does not depend on the skills of the forest officer but, however, it still does not obviate the chances of missing out.
The radio collar method, as indicated by the name, relies on radio collars being fixed on the tigers. Apart from the census, it also helps in keeping track of the tiger through the year and in a quick search and rescue operation in case the tiger is ambushed or hurt and stops moving. This is an accurate report for all tigers that have been collared (unless the tiger tends to venture in a salt water body which spoils the radio on the collars). However, not too many of the tigers across the national parks have collars fixed on them yet.
The camera trap method relies on the motion sensitive cameras installed in various parts of the national forests. These cameras capture the photos of all wild animals. The tigers captured on camera are identified by their unique stripes.
Empirical data like the increase (or decrease) of prey and vegetation in different parts of the forest also goes on to ratify the findings of the committee that is responsible for releasing the final population numbers.
The on-going census of 2018 has been designed to use a combination of all the above methods linked together with a more integrated use of technology – through an especially designed app M-STrIPES.
The Phase 1 of the exercise had all on-field personnel using the app to record data about the presence of the tiger through scat (poop), tree markings, pug marks etc and taking photos of the same. This would be uploaded along with the GPS coordinates of the location where the photo was clicked to a central server. Such photos combined with the coordinates made sure that the (intentional or unintentional) errors of reporting are removed from the data gathered.
The photos and data gathered also captures the flora and fauna in the area – which is the empirical data that is being used in the collation exercise.
The Phase 2 of the exercise utilizes the satellite data of the forest areas matching the empirical information collected in Phase 1
The Phase 3, which is the final phase under progress today, uses information from the camera traps (about 1500 nos in the wild) and pug marks/ DNA mapping through scat collected in the non-camera trap regions, to estimate the number of tigers. It will rely heavily on the information collated through the phase 1 and 2 as well to collate all information together.
In my view, there is no foolproof method of performing a census of wild tigers. All methods depend on human interventions. There are extremely high expectations from the participating individuals to go deep into the interiors of all jungles and capture data and information from inhospitable and dangerous conditions. Technology can only help reduce inadvertent (or, at times, deliberate) errors but cannot make this complex task accurate.
While I hope and pray that the efforts of all conservationists would have borne fruit and the tiger numbers would have climbed up in the last 4 years, I salute all forest officials for undertaking this difficult and challenging task at the risk of their personal safety and well-being.
Navya's blog 