USDA Forest Service

Pacific Southwest Research Station
Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Research Topics Ecosystem Processes

Sierra Nevada Ecosystems

Reintroduction of declining amphibians: a case study for the foothill yellow-legged frog (Rana boylii) and development of a quantitative database

Research Project Summary

The Research

Photo of a foothill yellow legged frogSpecies reintroductions provide a model for integrating practical and theoretical aspects of conservation biology. However, we currently lack a clear understanding of the factors that determine the outcome of reintroduction programs for many taxa. Combining pre-reintroduction research on ecology, genetics, and causative factors of declines with experimental reintroductions and rigorous monitoring, offers an approach that should increase reintroduction success rates. Amphibians present challenges as reintroduction subjects due to characteristics such as biphasic life cycles, low mobility, and patchy distributions.

The foothill yellow-legged frog historically occurred in foothill and mountain streams from northern Baja California to southern Oregon west of the Sierra-Cascade crest, to 1830m (6000 ft) in elevation. This species has experienced significant population declines especially in the southern part of its range (southern Sierra Nevada and south coastal California) and is currently listed as a California State Species of Special Concern and USDA Forest Service California Region Sensitive Species. In the Sierra Nevada, it apparently has disappeared from at least 66% of its historic range.

This project uses the foothill yellow-legged frog (Rana boylii) as a focal species to assess the ecological feasibility of a reintroduction. Three factors, that likely play a role in success of species reintroductions, are described and assessed in detail for this species: (1) pattern of and factors in its decline, (2) genetic variation and phylogeographic structure, and (3) habitat associations and suitability. The pattern and factors in decline are being analyzed using G.I.S. and will provide insights into potential locations for reintroduction. Genetic analyses are being done at the scale of the entire range of the species and for selected river basins, and both provide context for understanding genetic structure at the smaller scales. Habitat associations’ analyses are being conducted for large and small populations throughout the Coast Ranges and Sierra Nevada to determine key habitat features needed at target reintroduction sites.

photo of a streamAs second component of this project is the development of an amphibian reintroduction database. We are building a relational database for amphibians based on one developed for birds - the Avian Reintroduction Database (ARD) ( Earnhardt, J.M, D. Rentsch, E. VanderWerf, L. Faust, A. Wolf, and S.D. Thompson. 2003. The science of reintroduction: A survey of avian release programs. Poster presentation at Society for Conservation Biology Annual Meeting, Duluth, MN., July). The ARD contains over 80 variables for each species and release event. To date, we have evaluated the avian database relative to its appropriateness for amphibians and documented the modifications needed (see Lind 2006).


(1) Determine the primary causes of decline of the foothill yellow-legged through examination of species distribution (locality) data and corresponding spatial information on known and potential threats.
(2) Describe the genetic variation and structure of the foothill yellow-legged frog throughout its range and determine appropriate applications of this information to the conservation of the species, specifically with regard to the potential for reintroductions in areas of decline.
(3) Quantify habitat associations of the foothill yellow-legged frog and identify features of potential reintroduction sites based on habitat suitability for all life stages of the species.
(4) Develop a conceptual model for species reintroduction planning with considerations for: (a) source populations, (b) identification of areas where decline factors can be reduced or eliminated, (c) minimizing risk of negative affects on gene flow regimes, and (d) local habitat suitability.
(5) Develop a database of amphibian reintroduction projects to aid in coordination, planning and evaluation of these efforts.

Methods and design

Foothill yellow-legged frog Case Study

For decline factors, the analysis approach is to spatially relate the current status of R. boylii (present or absent) at historic localities to GIS-generated variables representing three hypothesized causes of decline: land use change, pesticides and other toxins, and global change. Through univariate and multivariate analyses we are evaluating up to fourteen environmental and two interaction variables representative of the three hypotheses. For genetic analyses, we used the Cytochrome B and ND2 mtDNA fragments and conducted phylogenetic and population genetic analyses. Habitat associations modeling focused on the microhabitat scale and we evaluated oviposition site use and selection coupled with larger scale evaluations of occurrence and relative abundance at breeding areas. A conceptual model has been developed to depict how these components fit together.

Amphibian Reintroduction Database

Because the ARD database exists as a model, this project first involves evaluating that database in terms of its appropriateness with modifications made as needed. Published literature and unpublished reports are being gathered and information is being gleaned from them to fill in the revised database structure.

Application of Research Results

Results from the case study on foothill yellow-legged frogs have direct and immediate application in the conservation of this species and in land/water management planning. In addition, these results make a substantial contribution to basic knowledge of the ecology and genetics of this species. The amphibian reintroduction database can be used by both restoration practitioners searching for current information, contacts, methodologies, and by scientists interested in evaluating programs with regard to species, geographic regions, and other factors.


photo of a map of the Sierra Nevada Ecoregion- Research Area California-WideVaries depending on objective. Analysis of decline factors and general genetic analysis will occur throughout the range of the species (southwestern Oregon and California, west of the Sierra-Cascade Crest). Local scale genetic analysis and habitat suitability will be focused on the Sierra Nevada foothills, especially the southern Sierra Nevada and adjacent populations to the north and west (inner Coast Ranges).

Lead Scientists/Collaborators

1) Lind, A.J.; 2) Shaffer, H.B.; 3) Davidson, C.D.; 4) Welsh, H.H. Jr., 5) Fellers, G.M., 6) Borisenko, A., 7) Earnhardt, J.M.

1) USDA Forest Service, PSW Research Station
Sierra Nevada Research Center
2121 Second Street, Suite A-101
Davis, CA 95528
ph: 530-759-1702
fax: 530-747-0241

2) Department of Evolution and Ecology
University of California, Davis, CA

3) Environmental Studies Program
California State University, San Francisco, CA

4) PSW Research Station
Redwood Sciences Laboratory, Arcata, CA

5) Western Ecological Research Center, U.S. Geological Survey, Point Reyes National Seashore, Point Reyes, CA  94956

6) Oregon Department of Environmental Quality, Laboratory Division - Northwest Region, Watershed Assessment Section, Portland, OR

7) Director of the Alexander Center for Applied Population Biology, Lincoln Park Zoo, Chicago, IL

Publications and Products

Lind, A.J. 2006. Development of a database on reintroductions, translocations, and associated captive breeding of amphibians. Final report, submitted to the IUCN Declining Amphibian Populations Task Force Seed Grant Program, Open University, Milton Keynes , United Kingdom . 14pp (March) ( pdf link).

Lind, A.J. 2005. Reintroduction of a declining amphibian: determining an ecologically feasible approach for the foothill yellow-legged frog (Rana boylii) through analysis of decline factors, genetic structure, and habitat associations. Ph.D. Dissertation, University of California , Davis . (March) 169 pp (Abstracts).

Last Modified: Aug 29, 2016 10:56:13 AM