Capture Probability and Survivorship of the Southern Two-Lined Salamander (Eurycea cirrigera) in Drought and Non-Drought Conditions

Abstract

Droughts represent a major disturbance in lotic systems, and likely negatively influence stream-inhabiting amphibian populations. However, because of the inability to predict droughts, empirical investigations examining the response of stream amphibians to drought are uncommon. We conducted a capture-mark-recapture (CMR) study of a population of Eurycea cirrigera (Southern Two-lined Salamander) at one stream from 2005-2010; during this five-year period several drought events occurred. This stochasticity provided an opportunity to examine the effects of drought on survivorship and capture probability of E. cirrigera. We found that capture probability was influenced by season and drought conditions. We also found that salamander survival was influenced by drought; monthly survivorship decreased from 0.96±0.03 during non-drought conditions to 0.79±0.03 during drought conditions. Our results suggest that drought leads to decreased survivorship of E. cirrigera and the effects of drought on capture probability varies by season. Increased capture probability, especially during the reproductive season, may be a result of salamanders seeking refuge in the stream as opposed to seeking refuge in the adjacent terrestrial environment.