Stream salamander persistence influenced by the interaction between exurban housing age and development

Exurban development is the fastest growing form of land use in the United States and already predominates southern New England. These housing developments alter stream ecosystems in a predictable manner described as urban stream syndrome. Yet, many stream salamanders are considered ubiquitous in the region. To determine what stream and watershed features enhance long-term population persistence in an exurban landscape, we compared the occupancy and abundance of two stream salamanders, Eurycea bislineata (northern two-lined salamander) and Desmognathus fuscus (northern dusky salamander), in watersheds that differed in housing density and time since construction. We estimated E. bislineata occupancy at 100% and found strong support for an interaction between the quadratic of average housing development age and housing density in watersheds influencing abundance. Abundance was sensitive to new and high-density housing developments and increased in watersheds that were more than 20 years post-construction when housing density was low. In comparison, D. fuscus occupancy was estimated at 18% and best explained by fine-scale stream features including soil temperature, water conductivity, dissolved oxygen, discharge, and sediment distribution. Notably, estimates of D. fuscus relative abundance within watersheds, including watersheds with low housing densities, were much lower than comparable estimates in the literature. We suggest an adaptive management approach to monitor and manage D. fuscus populations in the region. Future wildlife management decisions in exurban landscapes should consider interactions between housing age and density as well as development legacy effects.