Effects of Edge Contrast on Depredation of Artifical Avian Nests

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Abstract
We examined the effects of edge contrast on depredation of artificial avian nests at interfaces of mature stands and 2- or 12-year-old edges in an aspen (Populus spp.) cover type on a ruffed grouse (Bonasa umbellus) habitat management study area in central Pennsylvania [USA] from May to July 1988. One-hundred forty-nine of 360 nests (41%) were disturbed during the study. Suspected predators were American crow (Corvus brachyrhynchos) and blue jay (Cyanocitta cristata). Depredation of nests did not vary (P > 0.05) with edge contrast (age of edge or vegetative cover) or with time period. However, more arboreal (P < 0.05) than ground nests were disturbed; arboreal nests were particularly susceptible to predation by corvids. We conclude that regardless of the degree of edge contrasts, increased amounts of edge created by forest fragmentation will have a greater impact on productivity of birds, particularly to those species that nest above ground. We recommend additional experimental studies of depredation of avian nests along edges in different landscapes to better understand long-term trends in avian productivity.