Predation of artificial ground nests at two types of edges in a forest-dominated landscape

Artificial ground nests were placed in mature forests adjoining a) stands of young forest (vegetation <2 m high) where 'hard' edges were created, and b) stands of medium-aged forest (vegetation 2-8 m high) where 'soft' edges were created. Nests were placed at three distances from the forest edge (0 m, 50 m, and 100 m). Two northern bobwhite (Colinus virginianus) eggs were placed in each nest and monitored after 7 and 14 days of exposure between late May and mid July, 1994. Overall nest predation was 72% after 7 days of exposure and 85% after 14 days of exposure. Predation near soft edges was significantly higher than near hard edges after both 7 (p < 0.01) and 14 (p = 0.02) days of exposure. Predation near the edges was significantly higher than away from the edges after both 7 and 14 days of exposure (p = 0.02). There was spatial variability in predation which was unrelated to the type of edge or distance from the edge, possibly due to the movements of larger predators and microregional differences in predator densities within the landscape studied. Two motion-sensitive cameras were used to record the identity of predator species. Cameras documented 28 predation events during 1,728 hours of operation, caused by eight species of mammals: fisher (Martes pennanti), eastern chipmunk (Tamias striatus), red-backed vole (Clethrionomys gapperi), red squirrel (Tamiasciurus hudsonicus), deer mouse (Peromyscus maniculatus), black bear (Ursus americanus), eastern gray squirrel (Sciurus carolinensis), and striped skunk (Mephitis mephitis). The relationships between edges, predator assemblages, and nest success are complex; more studies at the landscape level are required to better understand the effects of these factors on avian population dynamics.