Research overview: national tiger population estimation methods

India's periodic all-India tiger estimation is among the largest wildlife surveys on Earth, combining sign-based occupancy across vast landscapes with camera-trap capture-recapture at intensively sampled sites. This overview surveys the double-sampling methodology used to scale local density estimates to national totals, and the statistical debates about its assumptions and uncertainty. Researchers have scrutinized how occupancy data are calibrated against camera-trap densities, how detection is modelled, and how confidence intervals should be reported. The exercise produces headline national figures that shape policy and funding, making methodological rigor consequential. The overview considers both the achievements of standardizing monitoring at continental scale and the critiques aimed at improving transparency and reproducibility. Robust national estimation is essential for tracking whether doubling commitments and reserve investments are actually working.