EFFECT OF CLEARCUT BORDERS ON DISTRIBUTION AND ABUNDANCE OF FOREST BIRDS IN NORTHERN NEW HAMPSHIRE

摘要

We compared numbers of forest bird territories between forest edge and forest interior areas to determine whether clearcuts affect bird abundance in adjacent forest. We then simulated the distribution of territories that would be expected if birds were neither attracted to nor repelled by clearcut borders by randomly locating 100 1-ha circular "simulated" territories on scale maps of the study plots, with the condition that simulated territories were located entirely within mature forest. Plots were divided into successive 50-m distance classes extending from clearcut borders 300 m into forest interior, and the distribution of territories of each species among 50-m distance classes was compared with the distribution of simulated territories. Red-eyed Vireos (Vireo olivaceus) and Hermit Thrushes (Catharus guttatus) were less abundant in edge areas, but the distribution of these species did not differ from the distribution of randomly placed simulated territories. We conclude that lower abundance of forest birds in edge areas is not necessarily evidence of edge avoidance but may be merely the result of the absence of suitable habitat beyond clearcut borders.