A comparative study of the diets and Morphometrics of two sympatric larval salamanders, Gyrinophilus porphyriticus, the Spring salamander (Green), and Pseudotriton ruber, the red salamander (Latreille)

Abstract

The aquatic larvae of Gyrinophilus porphyriticus and Pseudotriton ruber consumed a wide variety of prey over a study period of six months. A large proportion of the diets consisted of aquatic insect larvae, supplemented with non-insect and some terrestrial prey items. There appeared to be seasonal feeding preferences for each species, and the diets of each species were different from one another. Both species preferred certain prey items over others when their diets were compared to prey availability in the environment. Predator-prey size relationships were examined for both species by comparing volumes of the largest and smallest prey items in the diet with the snout-vent lengths and head widths of salamanders. A relationship for G. porphyriticus was not evident, but, for P. ruber, a significant size relationship was found. This suggested that ontogenetic diet shifts occur in larvae of P. ruber but not in larvae of G. porphyriticus in this study. Linear regressions were calculated for paired size measurements from each species. From these regressions, a significant difference in the slopes was detected when comparing standard length with head length for each species. However, a size ratio that distinguishes the two species could not be determined because the means of standard length/head length for each species, as well as for ratios from other size pairings, were insignificant.