Yosemite marks 10-year comeback for California red‑legged frog with 10,000th release — a model for threatened species recovery
Yosemite, California (Our Hesperia) – Yosemite National Park partners celebrated a decade of reintroduction on May 7, 2026, releasing the symbolic 10,000th California red‑legged frog, “Twain,” into Yosemite Valley — evidence of multi‑generation recovery after targeted removal and habitat restoration.
- 10,000th frog released: Zoo‑reared juveniles, including “Twain,” were released near Yosemite Falls on May 7, 2026.
- Collaborative model: NPS, USFWS, CDFW, Yosemite Conservancy and San Francisco Zoo & Gardens led rearing, restoration and monitoring.
- Threats addressed: Decades of invasive bullfrog removal and habitat restoration enabled multi‑generation establishment.
- Replicable approach: Rearing facility, staged releases and grant‑funded habitat work offer a template for other communities.
Key information
On May 7, 2026, partners held an event near Yosemite Falls to release several zoo‑reared juvenile California red‑legged frogs, including the symbolic 10,000th frog, “Twain.” See the California Department of Fish and Wildlife release for the official announcement.
The recovery effort is led by the National Park Service in partnership with the U.S. Fish and Wildlife Service, California Department of Fish and Wildlife, Yosemite Conservancy and San Francisco Zoo & Gardens. Event details appear on the NPS event page.
A dedicated rearing facility in San Francisco, opened in 2016 through an NPS–San Francisco Zoological Society partnership, raises frogs from wild‑collected eggs to one‑ and two‑year juveniles for release; see the San Francisco Zoo & Gardens video on the breeding program.
How the comeback unfolded
The California red‑legged frog (Rana draytonii) is the largest native frog in the western U.S. and California’s official state amphibian. Once common in Yosemite’s ponds, meadows and streams, the species disappeared from Yosemite Valley after invasive American bullfrogs and altered predator dynamics.
“After invasive bullfrogs eliminated red‑legged frogs from the area decades ago, we removed those threats and created conditions for recovery,” said Rob Grasso, aquatic ecologist at Yosemite National Park. “Today, multiple generations of frogs are established in Yosemite Valley.”
Park staff began sustained bullfrog removal efforts years before formal reintroduction work. Those efforts paired with habitat projects under the Merced River Plan rebuilt wetlands and streambanks, restoring conditions for native amphibians.
The rearing facility and science behind releases
A turning point came in 2016 when partners opened a dedicated rearing facility in San Francisco. Scientists collect eggs from wild populations outside Yosemite, rear tadpoles and juveniles in controlled conditions, and release one‑ and two‑year‑old frogs to improve survival prospects.
The program tracks survival, breeding and multi‑generation establishment. Monitoring shows released frogs not only survive but reproduce in the wild — creating the first self‑sustaining, multi‑generation population in Yosemite Valley in decades. Academic collaborators, including researchers from UC Santa Barbara, aided development of reintroduction methods. See the CDFW release and the NPS event page for monitoring details.
Funding, partnerships and voter‑approved grants
Funding combined federal, state and private sources. The California Department of Fish and Wildlife release notes that grants administered by CDFW — using funds approved by California voters — helped pay for habitat restoration.
Yosemite Conservancy provided donor funding for research and restoration; the San Francisco Zoo supplied breeding and rearing expertise; and the U.S. Fish and Wildlife Service provided technical oversight. As Kim Turner, acting field supervisor for the Sacramento Fish and Wildlife Office, said, “Our partners have been essential to the recovery.”
Threats addressed: bullfrogs and raccoons
Program leaders identified two historical threats: invasive American bullfrogs and elevated raccoon populations. Bullfrogs prey on juvenile and adult red‑legged frogs and can carry diseases harmful to native amphibians. Decades of bullfrog removals were essential to enable recovery.
Raccoon numbers were elevated when open refuse sites attracted scavengers until the 1970s. Controlling these indirect human‑caused food‑web changes was part of the long recovery timeline. (See ABC30 Fresno coverage.)
Monitoring and resilience amid climate challenges
Program managers expect ongoing challenges from drought, heavy storms and flooding, but monitoring shows frogs persisting and reproducing across multiple years. The partners plan to release roughly 830 juveniles in 2026 and have raised about 600 eggs for future releases, per the CDFW materials.
Voices at the event
Speakers at the May 7 ceremony highlighted long‑term collaboration. Rob Grasso described field work removing bullfrogs and improving habitat. Kim Turner emphasized federal partnership. Dr. Rochelle Stiles and Laura Patterson credited zoo breeding, voter‑approved state grants and donor support for the effort’s success.
Local and national media covered the story, noting Yosemite as the first site where reintroduction produced a self‑sustaining, multi‑generation population. See broader coverage from ABC30 Fresno and the NBC News / San Francisco Zoo feature on the breeding program.
Implications for Hesperia, California
The Yosemite recovery offers practical lessons and local impacts for Hesperia:
- Economic: Healthier park ecosystems support outdoor tourism across the Sierra and inland communities; recovery stories can boost visitation, field trips and local guide services.
- Political: The model demonstrates federal, state and private collaboration using voter‑approved grants and targeted funding — points relevant to local policy debates about stewardship and accountability.
- Social & educational: Schools and community groups can use Yosemite as a case study for ecology, civic engagement and citizen science opportunities.
- Practical: Techniques — invasive species removal, targeted habitat restoration and captive rearing with staged releases — can inform scaled projects for Hesperia waterways; the San Francisco rearing facility offers a partnership template for zoos, parks and universities.
Sources
- California Department of Fish and Wildlife news release
- NPS Stewardship Series event page
- ABC30 Fresno coverage
- NBC News / San Francisco Zoo video on breeding program
Reporting compiled from public agency releases and local coverage.
