The Foothill Yellow-legged Frog: Status Update and Steps for Compliance

Updated June 11, 2020 (originally published September 13, 2018)

By Brian Freiermuth, Wildlife Biologist

Foothill Yellow-legged Frog Life History

The foothill yellow-legged frog (FYLF), Rana boylii, is visually one of the more non-descript frogs in California, but it must gamble for survival. Although FYLF breed in relatively calm parts of streams, these areas are prone to scour from large late-season rains, or dry out if rains end early. Tadpoles must metamorphose before fall rains because they can be killed by rushing waters. To account for this, it is necessary for FYLF to breed early, and this transfers the most risk to eggs.

As a result, large portions of the reproductive effort each year can be lost, even in pristine systems. Although playing this high stakes game of “river roulette” has allowed the frog to exploit environments that other native species do not, land use conversion and other factors, especially dams, have increased these risks and led to declines in FYLF population. As a result, FYLF has been listed under the California Endangered Species Act (CESA) in many parts of its California range.

FYLF Regulatory Status in California

On July 7, 2017 FYLF became a candidate for listing under CESA. In late 2019, the CDFW published its staff review of the species and recommended that FYLF be listed as threatened or endangered, or not listed, depending on geography. The recommendation was adopted by the California Fish and Game Commission in early 2020. This geographic listing was based on recent genetic findings that described the species as being deeply divergent, meaning frogs in one part of the range are not as closely related to those in other parts as was previously thought. This was an unusual move, because a CESA candidate species is usually assessed across its range in California, and listing status is applied consistently across this range, without consideration of genetics. However, by considering the most up-to-date science and places where FYLF are still relatively common, this listing recommendation applies conservation where it is most needed and avoids placing onerous restrictions in areas where they are not currently as necessary. The Figure below shows the distribution of the FYLF clades, which correspond to CESA status of FYLF in California, by county. 

The Feather River and Northeast/Northern Sierra clades are listed as threatened; the East/Southern Sierra, West/Central Coast and Southwest/South Coast clades are listed as endangered. The only clade not listed under CESA is the North Coast Clade; this clade is not subject to CESA protections but is still a CDFW Species of Special Concern. For Species of Special Concern, measures for FYLF are reviewed and determined through the California Environmental Quality Act (CEQA) process and permitting activities administered by the CDFW. 

Take is defined under CESA as “to hunt, pursue, catch, capture or kill, or attempt to hunt, pursue, catch, capture or kill.” If take may occur as a result of a project, an Incidental Take Permit (ITP) from California Department of Fish and Wildlife (CDFW) must be obtained, and as part of the permit approval, take must be minimized and fully mitigated.

WRA Experts Weigh In 

For projects that may impact FYLF, a case-by-case assessment is necessary to determine if an ITP would be required. Generally speaking, if a project is to occur in perennial or intermittent streams in areas where the species is listed under CESA, and FYLF could be impacted, an ITP may be needed – unless it can be determined that no FYLF, in any life stage, would be subject to “take.” In the areas where the North Coast Clade of FYLF is present, Streambed Alteration Agreements (a permit issued by CDFW for projects that impact streams) are likely to have measures that require avoidance of FYLF, but no permit for take is required. As such, projects in the region where the North Coast Clade is present will still need to consider FYLF, but will not be required to acquire additional permits.

The U.S. Fish and Wildlife Service (USFWS) is also considering FYLF as a candidate for federal listing. A ruling on whether or not the species will move to candidacy should occur in 2020. Unlike CESA, the Federal Endangered Species Act does not mandate that protections are extended to candidate species during the candidacy. If FYLF is listed under the Federal Endangered Species Act, any take of FYLF would require a permit pursuant to this act. Habitat protections are also implemented as part of the listing.

Advice for Project Proponents

Proponents who operate inside the range of FYLF, including the North Coast clade, are advised to consider the species during the constraints analysis phase, project design phase, and CEQA/ permitting processes. Stream habitats, especially perennial and intermittent ones with coarse substrates, are the most important for FYLF, and as such, projects that propose activities in and around streams will require avoidance of the frog and/or an ITP if the species is present and cannot be avoided. Determining if FYLF is likely to occur at a site is a critical first step in choosing how to proceed.

For this reason, a habitat assessment and preliminary survey for FYLF can be extremely informative in determining whether or not avoidance measures or an ITP will be the best path for the project. Time of year, duration of work, and extent of the proposed work are also important considerations in helping to determine whether measures to avoid FYLF, including an ITP, are necessary. If your project is within the historic range of FYLF and will result in activities that are in or near stream habitats that could support it, some level of consideration of the frog will likely be necessary for your project.

FYLF Related Services Provided by WRA

WRA provides a range of services to assist our clients in navigating the regulatory environment, including several services that directly consider FYLF. The table below summarizes some of the services we provide. ITP-specific services are not applicable to geographical areas that overlap with the North Coast Clade of FYLF. 

For more information about our services, please contact Rob Schell, Senior Wildlife Biologist.

Source: Patterson, Laura, et al. Edited by Ryan Bourque et al., California Department of Fish and Wildlife, 2020, pp. 1-128, Report to the Fish and Game Comission: A Status Review of the Foothill Yellow-Legged Frog (Rana Boylii) In California.