Nest-Site Selection and Availability in Urban Populations of the Southern Two-Lined Salamander (Eurycea Cirrigera)

The southern two-lined salamander (Eurycea cirrigera) is a stream salamander common in the Georgia Piedmont and ubiquitous in both natural and degraded streams, including many urbanized streams in Atlanta, Georgia. These salamanders can serve as models for understanding how urbanization affects the life history of ecologically significant amphibians. Previous studies have found that salamander nests were more common in areas with gravel and cobble substrata and less common in areas with silt substrata. However, research investigating the differences in habitat availability between streams of varying degrees of urbanization is lacking. To evaluate the relationship between urbanization, nest-site selection, and stream substrate composition, we conducted a survey of stream substrate composition in 14 streams of varying degrees of urbanization in Atlanta, Georgia. At 25 random points and at every nesting site, we visually estimated embeddedness as well as percentages of substrate type and size, including silt, sand, pebble/gravel, cobble, boulder, and bedrock. We also recorded flow type (riffle, run, or pool) for each point. We used linear models and principal components analysis to compare stream substrate characteristics between nesting sites and random points. Here we present preliminary results describing the relationship between urbanization, stream substrate composition, and nest-site selection. Preliminary data analysis revealed significantly lower embeddedness and higher percent cobble in nesting sites compared to random points. Impacts of urbanization, such as increased sedimentation in streams, may influence nest-site availability and consequently salamander abundance