Project overview: Restore native amphibian populations, including by reintroducing Sierra Nevada yellow-legged frogs, California red-legged frogs and Yosemite toads to healthy lakes and meadows.

The backstory: Amphibian populations are threatened around the globe, as habitats vanish or deteriorate, and invasive diseases and species arrive. Since the late 1990s, our donors have supported efforts to study and save Yosemite’s native amphibians, including through surveys of lakes, ponds and meadows. In recent years, donor-funded work has focused on three imperiled amphibians: Yosemite toads, Sierra Nevada yellow-legged frogs and California red-legged frogs.

Through Conservancy-supported research, scientists have increased their understanding of the park’s population of Yosemite toads, a rare and endemic species. Starting in 2013, the Conservancy began funding targeted efforts to restore high country lakes and reintroduce once-common, now-endangered Sierra Nevada yellow-legged frogs. That effort has resulted in a measurable increase in yellow-legged frog numbers in Yosemite, one of few examples of a frog population rebounding as amphibians decline worldwide.

In 2016, with support from donors, scientists turned their attention to another imperiled amphibian, California red-legged frogs, which hadn’t been seen in the park in half a century. In recent years, biologists have reintroduced thousands of red-legged frog eggs, tadpoles and adults in Yosemite Valley, where the species is now successfully reproducing and regaining a foothold in the ecosystem.

The park’s successful amphibian work is anchored in innovative approaches to wildlife research and restoration. With donors’ support, scientists have been able to identify healthy habitat using environmental DNA (eDNA) techniques; study the prevalence of chytrid fungus, which causes the potentially deadly amphibian disease chytridiomycosis; use tiny microchips to monitor red-legged frogs; partner with the San Francisco Zoo to raise young amphibians in a protected space; and more.

This year: Through this 2021 grant, scientists are continuing the critical work of restoring and protecting native frogs and toads. They’re prioritizing efforts to protect amphibians from deadly disease, including by introducing chytridiomycosis-resistant yellow-legged frogs to alpine lakes. They’ll transport hundreds of red-legged frog eggs from private land to the San Francisco Zoo; the young frogs will stay at the zoo for a year or two, before being released in backcountry Yosemite lakes. Biologists will also prepare to release Yosemite toads, which Conservancy-funded research identified as particularly vulnerable to drought and climate change, in a park meadow. A reintroduction has never been attempted with Yosemite toads; if successful, this effort could set the stage for additional work to save the species.

Project partners: Yosemite National Park; University of California, Santa Barbara; and San Francisco Zoo.

Rob Grasso

Aquatic Ecologist, Yosemite National Park

Project Notes

“We are excited to continue our successful species recovery projects. Yosemite is one of the only places in the world where amphibian populations are increasing as a result of adaptive management.”