The animals and plants that only exist in captivity—and why time is running out to restore them to the wild

It was April in 1981 when a party of four camped for two days and nights on the forested slopes of Mount Evermann, the central peak of Socorro, a volcanic island in the Pacific some 400 kilometers southwest of Baja California, Mexico. Their fruitless search confirmed their suspicions: the Socorro dove, an endearingly tame bird unique to the island, had disappeared, eaten by the cats of Spanish colonists, pushed out by grazing sheep and shot from the sky by hunters.