Ecology of the Jollyville Plateau Salamander (Eurycea tonkawae: Plethodontidae) with an Assessment of the Potential Effects of Urbanization

Abstract

The Jollyville Plateau salamander, Eurycea tonkawae Chippindale, Price, Wiens, and Hillis, inhabits springs and wet caves of the Jollyville segment of the Edwards Plateau, Texas. The known range of this species is limited to six stream drainages, and most known localities are at risk of impairment from urban development. Our purpose was to gather needed autecological information on E. tonkawae and evaluate factors that may affect the distribution and abundance of the species. We conducted visual salamander surveys at nine stream sites across the Jollyville Plateau between December 1996 and December 1998. The survey sites were classified as undeveloped or developed based on watershed impervious cover estimates. We characterized the habitat for each site, including substrate type, discharge, and water quality. Salamander counts varied seasonally, but generally were higher during spring and summer. Salamander densities across sites were positively correlated with rubble and cobble substrate density as preferred cover, and negatively correlated with the standard deviation of water temperature, as expected for a spring-adapted species. In addition, we found that mean salamander densities at sites occurring in undeveloped watersheds were significantly higher than at developed sites, where specific conductance of the water was higher. The results of this study suggest that while habitat and seasonal factors influence surface salamander densities, E. tonkawae populations may be most vulnerable to effects associated with urbanization.