Population Density, Habitat Selection and Minimum Area Requirements of Three Forest-Interior Warblers in Central Missouri

Ovenbirds (Seiurus aurocapillus), Kentucky Warblers (Oporornis formosus), and Worm-eating Warblers (Helmitheros vermivorus) were censused in central Missouri to determine breeding population densities in three forest tracts large enough to satisfy minimum area requirements estimated in an earlier study. Densities of Kentucky Warblers and Ovenbirds were significantly higher in a large forest tract (>800 ha) than in two 300 ha forests. Worm-eating Warblers bred only in the large forest. Kentucky Warblers and Ovenbirds had larger territories in the two sites with lower population density. The three sites had similar vegetation structure but significantly different topography and edge/area ratios. Habitat selection, analyzed with principal component analysis and log-linear models, was significantly different among the three species and different among the three sites. Edge/interior ratio and topographic features contribute to differences in population densities observed among the three sites. Area requirements may be larger than those estimated by the incidence function.