Current Distribution, Relative Abundance, and Landscape-Level Habitat Associations of the Cerulean Warbler (Setophaga cerulea) Along the Lower Roanoke River in North Carolina

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Setophaga cerulea (Cerulean Warbler) has been inadequately monitored along the Roanoke River in North Carolina since a breeding population was discovered there in 1972. Our objectives were to estimate the Cerulean Warbler's current population size and distribution along the river, and evaluate landscape habitat characteristics in the Roanoke River Basin among areas used and unused by the same species. In May 2001 and 2011, we surveyed for singing male Cerulean Warblers, primarily by boat, along approximately 160 km of the Roanoke River from Weldon to Williamston in northeast North Carolina. We found Cerulean Warblers in three distinct groups along the Roanoke River during both survey years; however, we detected at least 32.4% fewer males in 2011 (n = 23) than in 2001 (n = 34). The landscape within 500 m of areas used by Cerulean Warblers had significanlty less crop cover, blackwater floodplain (i.e., swamp) forest, and variation in mean canopy height than unused landscapes we surveyed. These same differences existed at distances up to 1 km, but several additional dissimilarities became evident at this scale, including presence of more evergreen plantations and a greater fragmentation of the dominant forested land cover at used versus unused landscapes. We recommend continued monitoring of the Cerulean Warbler along the Roanoke River, increased habitat protection, and encourage an in-depth investigation into management strategies to sustain this population.