California Amphibian and Reptile Species of Future Concern: Conservation and Climate Change

Ecological niche models for all 153 reptile and amphibian species in California were built using Maxent to forecast the distribution of climatically suitable habitat under four future climate scenarios and eleven general circulation models for 2050. Risk was measured as both the percentage of currently occupied localities remaining suitable in the future (Point Ranking), and the change in suitable area within a minimum convex polygon of currently occupied localities (Area Ranking). The Point Ranking is based on the Distribution Trend metric from the Amphibian and Reptile Species of Special Concern (ARSSC) document and was designed to measure historical habitat loss. The Area Ranking metric is from NatureServe’s Climate Change Vulnerability Index, and the results from this study can be directly incorporated into other projects using that assessment tool. Depending on ranking metric, approximately 60-75% of reptile and amphibian species were predicted to experience little (<20%) direct loss of climatically suitable habitat by 2050. Reductions in climatic habitat suitability were predicted to be largest for reptiles in the southern mountains and deserts, with reductions for amphibians occurring statewide. The species ranked highest for risk include many that are already of conservation concern and tend to be endemic species with small ranges, such as the black toad, Bufo exsul. The modeled predictions for future habitat suitability presented in this study can be used to inform conservation of California’s reptile and amphibian diversity under climate change, particularly by prioritizing species and regions for monitoring and additional research.