Nest-Site Selection and Temporal Patterns in Habitat Use of Roseate and Common Terns

Abstract

Abstract Roseate Terns (Sterna dougallii) nest in a wide variety of habitats. We examined nest-site selection in a mixed-species colony of Roseate and Common (S. hirundo) terns on the interdune area of a barrier beach to determine species differences, to identify which characteristics at nest sites differed from the available habitat, and to compare nest-site preferences of early- and late-nesting Roseate Terns. Both species nested in the same area, but Roseate Terns nested under dense vegetation and Common Terns nested in more open sites. For Roseate Terns, cover within 0.5 m of the nest was greater than that within 1 m; the opposite was true for Common Terns. Cover within 5 m was similar for both species. Roseate and Common terns select different habitat features. Site characteristics of early- and late-nesting Roseate Tern nests differed. Late-nesting terns used sites with greater cover within 0.5 m, less cover within 5 m, taller vegetation, and with less visibility compared with early-nesting terns. Late-nesting Roseate Terns were still able to find sites in dense cover. At this colony, competition between the two species may not be limiting, and abundant sites remain available.