Amphibian Conservation

Mountain yellow-legged frogs (Rana sierrae and Rana muscosa) were once abundant across the Sierra Nevada, but have disappeared from more than 90% of their historical range. This decline has resulted primarily from the introduction of non-native fish into thousands of naturally fishless lakes and streams, and spread of the highly virulent amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). As a consequence, both species are now listed under the U.S. Endangered Species Act and are the focus of ongoing recovery efforts. 

In our early research on mountain yellow-legged frogs we described the frog’s current distribution and population trend, primary causes of decline, and effect of fish removal on frog abundance. 

Currently, we are developing methods to recover mountain yellow-legged frogs in the face of chytridiomycosis, the disease caused by Bd. A primary focus is on frog translocation, in which frogs are collected from populations that are thriving despite ongoing Bd infection and moving them to neary suitable sites that lack frogs. In partnership with the San Francisco and Oakland Zoos, we are also testing the effectiveness of frog reintroduction, in which early life stages (e.g., tadpoles) are collected from the wild, raised in captivity to adulthood , and then released back into the wild.