Postcard: Ranthambore.

The good news was embedded in the dirt trail that snaked its way through the brush: two prints--one belonging to an adult tiger and, within it, the distinct outline of a cub's paw. Later that March day, as the light began to dim in the dry, scrubby forest of India's Ranthambore tiger reserve, range officer Daulat Singh Shaktawat finally saw the new litter in the flesh. Atop a small hill, a tigress stood watch as her two cubs played. Marveling at the scene, Shaktawat moved closer until the mother snarled, keeping him at bay. "There's a thrill to the first sighting,"...