Love It or Leaf It: Site Selection of Breeding Treefrogs Based on Leaf Litter Subsidies

Breeding organisms rely on numerous environmental cues to determine optimal sites for oviposition. Site selection is often associated with factors that increase fitness, and the identification of these factors can help conservation efforts. For amphibians that breed in wetlands, the quality of terrestrial subsidies (e.g., leaf litter) can strongly influence larval survival and development by altering water chemistry and available nutrients. In this study, we examined the preference of breeding Gray Treefrogs (Hyla versicolor) for wetlands containing litter species of varying chemical quality. Based on previous studies of larval survival, we hypothesized that treefrogs would oviposit more eggs into wetland mesocosms containing litter with high nutrient concentrations and low phenolic concentrations. To test our hypothesis, we counted the number of eggs oviposited by treefrogs in artificial wetland mesocosms containing either Red Maple (Acer rubrum), Black Oak (Quercus velutina), or Eastern Hemlock (Tsuga canadensis) litter. We conducted this study over two breeding seasons. Counter to our hypothesis, we found that treefrogs preferred to oviposit in mesocosms containing maple litter, which contains high levels of both nutrients and phenolic acids. We discuss possible explanations for this result, including the possible anti-parasitic effects of phenolic acids. This is the first study demonstrating that breeding amphibians can differentiate between wetlands containing leaf litter species of differing chemistry. Given global declines in amphibian species concurrent with widespread changes in forest composition, our results emphasize the importance of considering leaf litter quality in wetland management and conservation efforts.