Nest-site selection by hooded warblers in bottomland and hardwoods of South Carolina
We measured habitat features at 45 nests of Hooded Warblers (Wilsonia citrina) and 45 non-use sites in bottomland hardwood habitats in the coastal plain of South Carolina during the breeding seasons 1993-1994 to determine features that affect nesting success. Hooded Warblers nested in switchcane (Arundinaria gigantea) and hardwood saplings or shrubs that averaged 1.76 ± 0.10 m (SE) in height. Nests were more concealed from above (P = 0.001) and from the side (P = 0.002) than surrogate nests placed at non-use sites but were less concealed from below (P = 0.002). Nest sites also had a greater number of potential substrates (P = 0.014) in the nest patch (5-m radius) and greater measures of vegetation density (P < 0.05) in the nest patch than non-use sites. Successful nests differed from unsuccessful nests only in the amount of fern cover in the nest patch (greater for successful nests, P = 0.012). Fern cover may influence nesting success through an effect on behavioral defense strategies. Nesting success of Hooded Warblers may largely be unrelated to fine-scale differences in vegetative characteristics of the nest site.