News Release

Rescue for Recovery: Biologists Team up with Zoos to Save Frogs on Brink of Extinction

December 16, 2015

Media Contacts:
Sacramento Fish and Wildlife Office
Sarah Swenty, Deputy Assistant Field Supervisor, External Affairs (916)414-6606,

Sequoia and Kings Canyon National Parks
Colleen Bathe, Chief of Interpretation, Education, and Partnerships (559)565-3130

San Francisco Zoo
Danny Latham, Director of Marketing (415) 488-7581

Oakland Zoo
Nicky Mora, Senior Manager, Marketing/PR (510) 632-9525 ext. 130

Media Advisory:
Media has permission to download/use photos and interviews:

Photo of Ash Mt Helibase

Photo by J. Bushell

Oakland, CA – December 16, 2015 - Critically endangered tadpoles emergency evacuated from the high Sierra and transported to Oakland Zoo and San Francisco Zoo have successfully morphed into healthy mountain yellow-legged frogs. The precious cargo, carefully collected by National Park Service biologists in August, was airlifted from remote locations in Sequoia and Kings Canyon National Parks. "Mountain yellow-legged frogs are getting hammered by non-native trout and disease, and urgent intervention was needed to keep two populations in Sequoia and Kings Canyon National Parks from disappearing," said Danny Boiano, Aquatic Ecologist at Sequoia and Kings Canyon National Parks. "The National Park Service is fortunate to partner with Oakland and San Francisco zoos on this project; along with several agencies and universities, we are all striving to recover these iconic endangered species."

Zoo biologists met the helicopter in Three Rivers, California and made a four hour drive with 270 tadpoles to the Bay Area, where the rare animals are now housed in quarantine areas at both zoos. "Oakland Zoo and San Francisco Zoo are committed to helping save these frogs, a California heritage species, a local animal that lives just a few hours away in the Sierra Nevada," said Victor Alm, Zoological Manager at Oakland Zoo. Within recent weeks, the tadpoles morphed into frogs and were specially treated for a deadly fungal disease called chytridiomycosis (chytrid).

Photo of Biologists working in the field

Photo by Larissa Perez / NPS

The highly infectious chtryid has caused more than 200 species of frogs and salamanders to become extinct within the last fifteen years. "Every continent that has amphibians has the disease. It has spread around the world very quickly," said Dr. Knapp, a research biologist with the Sierra Nevada Aquatic Research Lab at UC Santa Barbara. The rapid and severe decline of the Northern Distinct Population Segment of mountain yellow-legged frogs led the US Fish and Wildlife Service to list them for protection under the Endangered Species Act in 2014. "If this emergency salvage hadn’t occurred, considerably more than 90% of these individuals might not have survived, and we’d [potentially] lose both of these critical populations," said Dr. Steven Detwiler, Senior Scientist, with the Service’s Sacramento Office, which has helped coordinate the effort to save them.

Due to the chytrid crisis, zoos are teaming up with wildlife agencies to help save frog species in peril. Zoo keepers are treating the amphibians with a special type of bath which helps their bodies resist the deadly disease. "We have developed, in collaboration with UC Santa Barbara and researchers working on this project, an experiment to try and immunize these frogs," said Jessie Bushell, Director of Conservation at San Francisco Zoo. "The zoos re-infect the frogs short-term with chytrid, let them build up a minor infection, monitor them, and then treat them aggressively. Over a course of several months of this treatment, the frogs appear to develop a resistance to chytrid. And that is key to making sure the populations we’re putting back out in the wild have a chance at survival." In addition to the baths, San Francisco and Oakland zoos are "head-starting" the tiny frogs, raising them into healthy juveniles, better equipped to survive predators and chytrid when they are released back into the wild. "Head-starting allows us to introduce many more adult frogs that are disease-resistant, said Boiano. "Instead of 200 frogs in twenty years, we may give those populations 200 frogs in one year."

The conservation collaboration between the National Park Service, the US Fish and Wildlife Service, Bay Area Zoos, and volunteers is helping to save a native California species and give it legs to thrive and repopulate in the wild. Seeing flourishing frogs in healthy habitats is the ultimate goal of the rescue for recovery, so future generations are able to see and experience these animals first-hand, rather than reading about their demise in text books. If program efforts continue as planned, the goal is to release the yellow-legged frogs in Sequoia and Kings Canyon National Parks in summer of 2016.

Photo of Yellow Legged Frog

Photo by Marianne Hale / SF Zoo

The mountain yellow-legged frog complex in the Sierra Nevada is comprised of two species (Rana muscosa and Rana sierrae) that inhabit high elevation aquatic habitats. Although historically abundant, these frogs have been extirpated from more than 92 percent of their geographic ranges, with many of the remaining populations depleted. Declines were first recognized during the 1970s and have accelerated markedly since the 1990s. The realization that these patterns would rapidly place these species at risk of extinction led to Endangered listings for both species under the U.S. Endangered Species Act. Mountain yellow-legged frogs in the Sierra Nevada occur between the headwaters of the Feather River and the headwaters of the Kern River. Rana sierrae occupies the northern and central Sierra Nevada south to the vicinity of Mather Pass (Fresno County), whereas Rana muscosa occupies the Sierra Nevada south of this area.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals, and commitment to public service.

The fundamental purpose of the National Park Service is to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations. The mission of Sequoia and Kings Canyon National Parks is to protect forever the greater Sierran ecosystem - including the sequoia groves and high Sierra regions of the parks - and its natural evolution, and to provide appro¬priate opportunities to present and future generations to experience and under¬stand park resources and values.

Established in 1929, the San Francisco Zoo & Gardens connect people to wildlife, inspire care for nature and advance conservation action. An urban oasis, the Zoo & Gardens are home to over 1,000 exotic, endangered and rescued animals representing more than 250 species as well as seven distinct gardens full of native and unusual plants. Located at the edge of the Pacific Ocean where the Great Highway meets Sloat Boulevard, the Zoo is open 365 days a year from 10 am to 5 pm and is accessible by San Francisco Muni "L" Taraval line.

The Bay Area's award-winning Oakland Zoo is home to more than 660 native and exotic animals. The Zoo offers many educational programs and kid's activities perfect for science field trips, family day trips and exciting birthday parties. Oakland Zoo is dedicated to wildlife conservation onsite and worldwide. Nestled in the Oakland Hills, in 500-acre Knowland Park, the Zoo is located at 9777 Golf Links Road, off Highway 580. The East Bay Zoological Society (Oakland Zoo) is a nonprofit 501(c)3 organization supported in part by members, contributions, the City of Oakland and the East Bay Regional Parks.

The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect, and enhance fish, wildlife, plants, and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals, and commitment to public service. For more information on our work and the people who make it happen, visit Connect with our Facebook page, follow our tweets, watch our YouTube Channel, and download photos from our Flickr page.