Does Exposure to Predator Cues Influence Movement Behavior of Postmetamorphic Juvenile Rana aurora?

Abstract

Exposure to predators during early life stages can alter behavioral and physical traits during ontogeny. This is important for biphasic amphibian species because juvenile movement behavior can be shaped by carry-over effects of the larval environment and direct effects of abiotic conditions in terrestrial habitats. We explored the interaction of aquatic predator cue exposure, juvenile morphology, and abiotic terrestrial conditions on the movement behavior of postmetamorphic Northern Red-legged Frogs (Rana aurora). We quantified carry-over effects of aquatic predator cues and direct effects of substrate conditions on individual movement behavior using a combination of seminatural enclosed runways and powder tracking assays. We found a latent effect of aquatic condition, such that crayfish-exposed individuals had greater relative body condition at metamorphosis, and all predator-exposed individuals had larger body lengths relative to controls. Terrestrial conditions were the dominant factor shaping movement behavior. During runway movement assays, individual conditional movement displacement was likely greater in dry soil and low humidity conditions than in moist conditions with high humidity. For nocturnal powder tracking assays, individuals were more likely to have greater path distances during warmer temperatures, whereas paths were less meandering in cooler, dry conditions. Morphologically larger individuals moved greater distances only during the powder tracking assays. We observed latent effects of aquatic predator exposure on juvenile morphology; however, the relationship between these changes and the relative importance of direct environmental conditions in shaping movement behavior is unclear. Our results demonstrate the interconnected nature of aquatic and terrestrial environments in shaping the movement of juvenile amphibians.