The bulk of the tiger population is in the Sundarbans (marshlands at the bottom of the Ganga-Brahmaputra delta). Anecdotally, many of the Sundarban tigers are man-eaters and there is a tacit policy to not go after the ones that happen to kill humans. This keeps the poachers and encroachers away, but also makes any census nearly impossible to conduct. I would not put too much faith in these reported numbers.