For a bird species hanging on by a thread, even a single successful rescue can carry enormous weight. In southern India, a six-month-old Indian vulture was treated for a leg injury and released back into the wild, offering a hopeful sign for one of the world's most threatened scavengers. What happened? A young Indian vulture, also known as Gyps indicus, was rescued on June 10 at the Sri Ramadevarabetta Vulture Sanctuary in Ramanagara after the F…