Environmental drivers of surface activity in a population of the eastern red-backed salamander (plethodon cinereus)

Understanding the influence of spatiotemporal variation in environmental factors on phenology is crucial for determining the effects of climate change on amphibian populations. Here we quantify the relative influence of temperature and precipitation on surface activity of a terrestrial salamander, the Eastern Red-Backed Salamander (Methadon cinereus) in Richmond, Virginia, USA. Specifically, we used spatial capture-recapture methods to test the influence of different metrics for temperature and precipitation on baseline detection probability. We found that soil temperature, particularly at 30 cm below the surface, is a better predictor of detection than air temperature or cumulative precipitation; however, greater cumulative precipitation resulted in a higher detection probability. We also show that a quadratic effect was favored in all scenarios suggesting this species has an optimal soil temperature and cumulative precipitation for surface activity during a particular year. The highest detection probability was associated with 12.6 degrees C at 30-cm below the surface and 0.75 cm of cumulative precipitation during the 2-d period prior to the survey occasion. In addition to contributing knowledge on the specific environmental metrics that best predict surface activity for P. cinereus, this work illustrates the importance of incorporating soil temperature measurements in capture-mark-recapture studies of terrestrial salamanders. For projects with limited resources, our work indicates which fine-scale environmental measurements associated with terrestrial salamander activity in the southern portion of the range are best.