Inter- and intra-specific dietary overlap in predacious bi-phasic salamanders

When multiple species with similar trophic niches co-occur in an ecosystem, foraging, refuge, and breeding microhabitats are predicted to be partitioned in order to enable their coexistence. However, few studies have examined potential niche partitioning among vertebrates with a bi-phasic natural history, such as stream salamanders. In addition to microhabitat, the coexistence of multiple species and life-stages is likely facilitated by the partitioning of diet. As plethodontid stream salamanders have an aquatic larval stage and a semi-aquatic adult stage (i.e., post-metamorphic), the diets of multiple species and life-stages can elucidate patterns in their community structure. Specifically, dietary overlaps can be used to evaluate the level of niche overlap and thus, potential competition among different species and life-stages. In this study, we non-lethally examined the dietary overlap among five predacious aquatic larval and three semi-aquatic adult stream salamander species in southeastern Kentucky. Our data illustrated both inter- and intra-specific dietary overlaps among the stream salamander community. We additionally observed dietary overlaps among all adult salamanders and their larval counterparts. We found differential dietary clustering and separation among some of the species and life-stages. Though not directly tested in this study, our results are suggestive of selection/constraint to species- and life-stage-specific foraging microhabitats.