Abundance and productivity of forest songbirds in a managed, unfragmented landscape in Vermont

Effective conservation of forest songbirds requires knowledge of responses to landscape pattern. We studied a breeding songbird community in a landscape characterized by scattered openings in a forest matrix in Vermont, 1993-94. We measured species composition, abundance, and fledgling brood density in the forested areas of 10 500-ha sites; we compared a group of 5 disturbed-canopy sites (less than or equal to 10% canopy disturbance) with a control group of 5 undisturbed-canopy sites. We conducted 456 point counts to determine species composition and abundance, and we conducted 60 line transect surveys to estimate fledgling brood density as a measure of productivity. Adult densities were not different between groups (P > 0.05) for 18 species listed as priority for conservation, although power was low. Combined broad densities of all species, Neotropical migrants, and ground nesters were not different among groups (P > 0.05). Brood densities of 3 Neotropical migrants also were not different (P > 0.05). However, combined broad density of area-sensitive, forest interior species was greater on control sites (P < 0.05). At the scale of this study, a minimal amount of canopy removal in the extensively forested landscape did not affect abundance and overall productivity of songbirds inhabiting the remaining forest, but canopy removal had begun to suppress productivity of some forest interior species.