Efficacy of Created Wetlands For Amphibian Population Persistence in Forested Ecosystems

A great deal of attention has been given to wetland acreage due to the “no net loss” policy over the past two decades, but much less attention has been given to the ecological integrity of these same wetlands. Due to their importance in wetland ecosystems and their status as an indicator taxon, amphibians can serve as models for understanding the roles that seasonal and semi-permanent wetlands play in ecosystem function. For amphibians, use of poor-quality habitat may result in a reduced number of offspring, reduced quality of offspring, and/or reduced survival in the terrestrial environment. Any or all of these outcomes have the potential to seriously jeopardize the long-term persistence of amphibians on the landscape. To evaluate the success of recently created wetlands in providing suitable habitat for amphibians, we sampled two reference and four recently created wetlands in central Illinois in 2017 and 2018 using drift fence pitfall trap arrays. Using Bayesian mixed-effects models, we assessed the effects of climatic and landscape variables on amphibian wetland use, recruitment, and productivity for four species (Silvery Salamanders; Small-mouthed Salamanders; Spring Peepers; and Wood Frogs). Further, we evaluated the body condition of both breeding adults and emerging metamorphs using a scaled mass index (SMI) for each species. Our analyses of species’ responses to wetland-level covariates suggested a less specific influence of wetland classification (created vs. reference); rather, our analyses highlight the year-to-year variation typical of wetland-breeding amphibians. Silvery Salamanders, male Wood Frogs and male Spring Peepers breeding at reference wetlands had higher SMI values than individuals breeding at created wetlands; we did not observe a difference in SMI of post-metamorphic juveniles emerging from the wetlands.