Life-history costs of reproductive behaviors in a wetland-breeding amphibian

Studies examining the association between life-history strategies and behavior can help inform our understanding of the fitness consequences of reproductive behaviors. Breeding migrations are common in numerous taxa and often represent an important reproductive cost. We examined body mass changes of spotted salamanders (Ambystoma maculatum) during their seasonal breeding migrations to determine the influence of breeding behaviors on reproductive costs. We sampled salamanders entering and exiting a 0.92-ha ephemeral wetland in the North Carolina Piedmont using a 400-m drift fence completely encircling the wetland. Traps were checked daily during annual breeding migrations in mid-January to early March of 2013 and 2014. The relationship between body mass changes and explanatory factors including sex, duration of stay at wetland, and distance between site entrance and exit were examined using a set of candidate linear mixed models selected a priori and compared using Akaike's information criterion. Female salamanders lost a greater percentage of body mass during the time in the wetland than males as a result of oviposition. Model selection identified duration of stay as the most important predictor of female body mass change with greater duration of stay associated with lower mass loss. In males, percentage mass loss was most closely associated with site entrance–exit correspondence with greater distance between entrance and exit sites associated with greater mass loss. These data demonstrate both the importance of wetland entrance–exit sites and duration of stay at the wetland in determining mass change during spotted salamander reproduction and also that these relationships can differ as a function of sex. Taken together, our findings provide a potential link between behavior, life-history cycles, and costs experienced during reproduction.