The intersection between locomotor performance, prey consumption rate, and morphology under perceived competition and predation in Ambystoma maculatum larvae

Whereas prey tend to reduce conspicuousness, predators remain active to locate their prey. In particular, mesopredators (i.e., predators situated in the middle of two trophic levels) may be subjected to opposing pressures. Locomotor performance influences predator-prey interactions, and together with behavior can be constrained by morphology. In this study, we test how locomotor performance and foraging behavior of larvae of the predaceous amphibian Ambystoma maculatum are influenced by morphology and exposure to chemical cues from predators and competitors. We test whether tail-injured and uninjured larvae differed in morphology, locomotor performance, and feeding rate. Larger individuals showed higher locomotor performance and prey consumption rate. These were not correlated, but the latter increased subsequent locomotor performance. Neither perceived predators nor competitors affected swimming speed or prey consumption rate. Body size was positively correlated with prey consumption rate only in those individuals not previously exposed to chemical cues from predators and competitors. Finally, tail-injured larvae were smaller, but did not experience reduced speed or prey consumption rates.