YOSEMITE — Thanks to the Yosemite Conservancy and the San Francisco Zoo, Yosemite National Park now has the makings of a robust population of California red-legged frogs in Yosemite Valley, after decades of absence.
In the early 1950s American bullfrogs were introduced in Yosemite Valley. According to the Department of Fish and Wildlife, American bullfrogs were intentionally introduced into the western United States as a food source and for biological control of insects, and may have been accidentally introduced into some areas during fish stocking.
Yosemite rangers explain that bullfrogs are an invasive species and will eat anything that fits into their mouths, including native turtles, amphibians, small mammals, and birds. The Yosemite National Park aquatics program successfully removed bullfrogs, leaving an open niche in the Valley for the California red-legged frog, a native species.
Unlike the invasive bullfrog, the California red-legged frog (Rana draytonii) is a federally listed species and is in decline throughout most of California. On May 10 of this year, these California red-legged frogs were released into Yosemite Valley. The frogs released here in May were collected as eggs from a donor population and raised to adulthood at the San Francisco Zoo. All told, thousands of tadpoles and hundreds of adult red-legged frogs have been released at various locations over the past three years.
Yosemite Conservancy says scientists will continue to bolster the park’s amphibian and reptile populations, working with the San Francisco Zoo to rear young turtles and red-legged frogs, using new insights to identify ideal release sites in the Valley, and carefully moving yellow-legged frogs to additional high-altitude lakes.
Ultimately, they believe these efforts will help all three species continue to regain their footholds in the Sierra Nevada ecosystem. Welcome home, little friends.