India, Jan. 23 -- It was a meeting with the legendary conservationist Fateh Singh Rathore in 1976 that changed Valmik Thapar's life.

Rathore was then director of the Ranthambore Tiger Reserve in Rajasthan, and took the passionate 24-year-old conservationist under his wing.

It was very rare to see a tiger at Ranthambore in those years. One might get a fleeting glimpse at night, often only if bait was set first. There were few tourists, fewer jeeps, and almost no hotels.

This was three years into Project Tiger, an initiative launched by the government of India in a desperate bid to keep these majestic beasts from dying out amid widespread poaching and habitat loss. The tiger population was estimated at 268 individuals at the time. (There...