EFFECTS OF VERNAL POOL HYDROPERIOD ON LARVAL OCCUPANCY OF THREATENED CALIFORNIA TIGER SALAMANDERS IN THE CENTRAL VALLEY.
Amanda M. Kissel; Conservation Science Partners; 5 Old Town Square, Suite 205, Fort Collins, CO, 80524; (970) 484-2898; amanda@csp-inc.org; Eric C. Hansen, Meghan Halabisky, Rick D. Scherer, Maureen E. Ryan, Brett G. Dickson
Understanding the link between hydroperiod and persistence of wetland obligate species is critical for managing wetlands under climate change, particularly for vernal pools in the Central Valley of California which maintain a number of threatened and endangered species. We explored the relationship between larval occupancy of the federally listed California tiger salamander (Ambystoma californiense) and hydroperiod dynamics of vernal pools in the San Joaquin Valley, California. We used a spectral mixture analysis, a remote sensing technique to identify water on the landscape, coupled with Bayesian mixed-effects models to estimate daily surface area of 150 vernal pools over a 20-year timespan. We then modeled occupancy of A. californiense larvae as a function of site attributes and hydroperiod covariates developed from the surface area estimates. We found that the probability of occupancy decreased (from 0.41 to 0.26) as hydroperiod length increased, suggesting A. californiense larvae occupy vernal pools that are likely to dry sooner if precipitation is reduced under future climate change. Our results demonstrate how these methods can be used to identify wetlands that are likely to be occupied by A. californiense larvae under climate change scenarios, information that can proactively guide management decisions for A. californiense and other wetland-obligate species.
Ecology and Conservation of Amphibians and Reptiles III