Progress of the Rana sierrae program
at San Francisco Zoological Gardens


Rana sierrae

Common Name(s)

Sierra Nevada Yellow-legged Frog

Region where program is based

North America

Country where program is based

United States

The authority that recommended this species for an ex situ program

Conservation Needs Assessment Workshop

Has a genetic analysis been performed on wild populations to define the target taxon, i.e., verify that single, viable Evolutionarily Significant Units (ESU's) that are managed as separate populations, are not confounded by cryptic species or polymorphisms?


Name of the institution managing the ex situ population

San Francisco Zoological Gardens

Year the program started


Is at least some portion of the captive population maintained in range country?


Are sufficient resources available to manage the ex situ population?

Are adequate numbers of skilled staff available with the appropriate ex situ amphibian experience?

Is sufficient space available for the required population size?

Additional Support required

Has a Taxon Management Coordinator for the ex situ population been appointed?


Taxon Management Coordinator

Jessie Bushell of San Francisco Zoological Gardens

Has a Taxon Management Group or Recovery Team been established?

Has a Taxon Management Plan, Recovery Plan or Species Action Statement been written?

Web link to Taxon Management Plan

Have Husbandry Guidelines been written?

Web link to Husbandry Management Guidelines

Have any knowledge gaps in the species biology or in their interaction with potential threats been identified that could benefit from research using the ex situ population?

Have founder needs been calculated using the AArk Amphibian Population Management Guidelines ?

Have sufficient potential founders been collected? ( AArk Amphibian Population Management Guidelines recommends a minimum of 20 pairs of found animals).

Is the ex situ population managed by nationals from the range country?


What tools are used to maximize retention of genetic diversity?

Has the population produced viable offspring?


Have the first generation captive-bred animals bred successfully?

Is the ex situ population housed in permanent isolation from other populations occurring outside its range?

Is work being supported to study and mitigate threats to the species in the wild, either by the institution or by a regional wildlife agency?

Have captive-bred or captive-reared animals been released into the wild?

If releases were undertaken, have disease screening protocols or veterinary health checks been conducted prior to releases to the wild?

Is follow-up work being carried out to monitor progress of the released animals?

Is the taxon again secure in the wild, even if it might still require some ongoing in situ management? i.e. has the need for a captive assurance population been obviated such that we can call this a successfully terminated captive rescue program?



2015: The Zoo houses a population of adult R. sierrae that were former wild-caught research animals from populations which are now extinct in the wild. This group is the founder stock for a potential conservation breeding colony to produce frogs for potential release back into the wild. In 2015 the Zoo released 97 frogs into two lakes in Lake Tahoe Basin and continued to rear an additional 73 frogs that were too small for release. The Zoo collaborated with Sequoia-Kings Canyon National Park where some populations of frogs have been extirpated and many more are on the brink of disappearing due to an active Bd outbreak. The Zoo raised 188 salvaged wild-caught metamorph frogs and eggs/tadpoles to adulthood which were inoculated prior to reintroduction to minimize pathogen impacts.