50 YEARS OF PROJECT TIGER

How are these numbers counted?

• In 1973, forest staff would use glass and butter paper to track tiger pugmarks. Every tiger has a unique and individual footprint -- like human fingerprints -- that helps in tracking. Rangers would trace the joint marks off the foot and trace it on butter paper to draw and record the footprint with the idea of using it to track that particular tiger in the future. However, it's not reliable as the pugmarks differ when a tiger is standing, resting, or running & this adds discrepancies to the process.
• Over the years the practice evolved into a statistical method of counting. Forest staff turned to the capture-mark-and-recapture method, which is largely used to estimate the population based on a sample. Data on individual tiger photo-captures is used in combination with data on prey, habitat, and anthropogenic factors to arrive at tiger population estimates for each landscape.
• According to the National Tiger Conservation Authority, the camera traps are set up in areas known to be frequented by the big cat such as animal trails, nullahs, riverbeds, and car tracks. The cameras are placed at knee height concealed from the general view of the animal camouflage to blend in the environment. The camera traps are set in pairs to capture both sides of the tiger.
• India is divided into five zones for the survey - Gangetic Plains, Central India and Eastern Ghats, Western Ghats, North Eastern Hills and Brahmaputra Flood Plains, and Sundarbans. During the 2018 assessment, a total area of 381,400 square km was surveyed with 26,838 camera trap locations in 141 sites.
• "The tiger numbers are expected to be significantly higher than what the reports indicate since camera traps are only set up in the protected areas. With the increasing numbers of the big cat, they do venture out beyond the limits of national parks where we don't have camera traps,