Every day, little by little, our species is creating new islands. These are not islands in the sea. They are patches of forest, grassland, mountainside, and swamp that encompass what remains of the wild. Unlike islands dotted across the sea, though, there are sometimes pathways between these protected swaths that permit organisms to traverse the small percentage of their range that remains open to habitation. In the case of central India’s tigers and leopards, these wildlife corridors are critical for survival.

Zoologists Sandeep Sharma and Trishna Dutta of the Smithsonian Conservation Biology Institute, along with a host of coauthors, have just published a pair of studies that used felid feces to gauge the genetic diversity of tigers and leopards in central