Effect of Border-Edge Cuts on Birds at Woodlot Edges in Southwestern Pennsylvania

Abstract

Many edge- and shrub-nesting bird species have exhibited population declines in the United States over the last 30 years, despite increasing abundance of edge habitat. Declines may be related to quality of edge habitat, rather than quantity. Border-edge cuts are a management technique used to modify existing edge habitat by creating a shrub transitional zone 15-40 m in width at the forest-field edge. To determine if the increased shrub growth in border-edge cuts affected edge-nesting birds, we tested the hypotheses that bird communities in border-edge cuts versus uncut edges have (1) greater abundance and species richness, and (2) greater nest success. We conducted line transect bird counts and nest searches in 12 pairs of border-edge cuts (2-3 yr old) and uncut edges. Border-edge cuts had greater horizontal (P = 0.008) and vertical (P < 0.001) cover than uncut edges. Avian abundance was higher in border-edge cuts than in uncut edges (P = 0.034), but species richness did not differ (P = 0.596). Of 60 bird species recorded, 13 were found only in border-edge cuts, and 23 were found only in uncut edges. Border-edge cuts supported more shrub- and edge-nesting species, while uncut edges contained more woodland species. There was no difference in Mayfield nest-success probabilities between the 2 edge types (P = 0.337). Evidence at depredated nests suggested snakes were the primary nest predators. Border-edge cuts may provide habitat for some declining populations of avian shrubnesting species in Pennsylvania, but evidence of effects on reproductive success was inconclusive.