Designing suburban greenways to provide habitat for forest-breeding birds
Appropriately designed, greenways may provide habitat for neotropical migrants, insectivores, and forest-interior specialist birds that decrease in diversity and abundance as a result of suburban development. We investigated the effects of width of the forested corridor containing a greenway, adjacent land use and cover, and the composition and vegetation structure within the greenway on breeding bird abundance and community composition in suburban greenways in Raleigh and Cary, North Carolina, USA. Using 50 m fixed-radius point counts, we surveyed breeding bird communities for 2 years at 34 study sites, located at the center of 300-m-long greenway segments. Percent coverage of managed area within the greenway, such as trail and other mowed or maintained surfaces, was a predictor for all development-sensitive bird groupings. Abundance and richness of development-sensitive species were lowest in greenway segments containing more managed area. Richness and abundance of development-sensitive species also decreased as percent cover of pavement and bare earth adjacent to greenways increased. Urban adaptors and edge-dwelling birds, such as Mourning Dove, House Wren, House Finch, and European Starling, were most common in greenways less than 100 m wide. Conversely, forest-interior species were not recorded in greenways narrower than 50 m. Some forest-interior species, such as Acadian Flycatcher, Hairy Woodpecker, and Wood Thrush, were recorded primarily in greenways wider than 100 m. Others, including ground nesters such as Black-and-white Warbler, Louisiana Waterthrush, and Ovenbird, were recorded only in greenways wider than 300 m. Landscape and urban planners can facilitate conservation of development-sensitive birds in greenways by minimizing the width of the trail and associated mowed and landscaped surfaces adjacent to the trail, locating trails near the edge of greenway forest corridors, and giving priority to the protection of greenway corridors at least 100 m wide with low levels of impervious surface (pavement, buildings) and bare earth in the adjacent landscape.