Responses of Rail Productivity to Water Level Variability and Factors Affecting Rail Broadcast Survey Results

Virginia rail (Rallus limicola) and sora (Porzana carolina) (hereafter “rails”) populations are thought to be declining and we examined habitat variables potentially affecting productivity of 75 Virginia rail and 22 sora nests in Maine during 2010-2011. We identified the mechanisms for nest failure (nest scale) and characteristics of wetlands (wetland scale) that predict reproductive success with logistic-exposure models and an information-theoretic approach. Our results suggest that water-level variation is a positive predictor of rail nest success and rail density in Maine wetlands. Hydrologic variation creates low-sloped wetland edges where emergent plants thrive. Wetlands with large areas of shallow depths and abundant emergent vegetation improve habitat condition for nesting rails. The presence of a waterfowl impoundment did not affect water-level variability, nest survival, or clutch size in our models.