SAVING THE mountain yellow-legged frog

The mountain yellow-legged frog was once the most abundant amphibian in the Sierra Nevada and Transverse Ranges of Southern California. Only a few decades ago, it was difficult to walk around many of California’s alpine lakes without tripping over these diminutive “mountain gnomes.” Today the hardy survivors of freezing, high-elevation winters are vulnerable to a host of modern threats, which have driven the frogs extinct in more than 93 percent of their old mountain homes.

The mountain yellow-legged frog has two different populations that have been declared separate subspecies: a northern and central Sierra Nevada population and a southern Sierra Nevada and Southern California population. Both populations are adapted to high-elevation habitats without aquatic predators. So it’s not surprising that the main reason for the frog’s decline is the California Department of Fish and Game’s introduction of nonnative trout to alpine lakes. These stocked fish prey upon tadpoles and juvenile frogs, and scientists predict that the yellow-legged frog could be extinct within decades. It has disappeared from the vast majority of known historical locations, and most of the largest remaining populations have recently fallen to near-collapse.