Breeding biology and habitat associations of cerulean warblers in southern Indiana
The Cerulean Warbler (Dendroica cerulea), a once common summer inhabitant and breeder in southern Indiana, has declined at both local and continental population levels. Effects of specific silvicultural practices on the distribution and abundance of the Cerulean Warbler is unknown. During the summers of 2005 & 2006, Cerulean Warblers were surveyed within the Morgan-Monroe and Yellowwood state forests, as well as the Hoosier National Forest in southern Indiana. Three forest types were surveyed; unharvested reference sites were compared with single tree selection treatments and treatments where a combination of group and single tree selection was used. Mean bird abundance was estimated from bird surveys to determine if a correlation exists between silvicultural regimes and Cerulean Warbler abundance. Cerulean Warblers were located in all treatment types, with no significant differences in abundance between or among treatment types examined. These results suggest that uneven-age management practices, such as single tree and group selection harvesting, provide suitable breeding habitat for Cerulean Warblers.Knowledge of Cerulean Warbler (Dendroica cerulea) male pairing status based on song rates and frequencies, as well as familiarity with non-song vocalizations could be an effective management tool when studying this species. Cerulean Warblers were recorded throughout the breeding season, and 18 song variables were measured and compared between paired and unpaired males using Logistic Regression. Unpaired males had higher song rates and higher minimum frequencies than paired male counterparts. Female and fledgling call notes were also recorded and quantitatively analyzed. These analyses offer further understanding of intraspecific call functions of this species.