Ground nest predation might not be higher along edges of Neotropical forest remnants surrounded by pastures: evidence from the Brazilian Atlantic forest

Several studies indicate that nest predation is higher along edges than in habitat interiors mainly due generalist predators arising from or proliferating in the surrounding matrix. Recent reviews demonstrate however that this is far from universal, in part because studies are strongly biased in temperate regions. Far fewer are known from the Neotropics and just a handful of studies have been carried out in the biologically-rich but severely fragmented Atlantic Forest of Brazil. Here we tested the influence of edge proximity on ground nest predation in a large (21,787 ha) Atlantic forest reserve. The experiment was carried out using chicken and quail eggs in 12 transects with 500 m in length, half of which parallel to internal edges (dirt roads) and half parallel to external edges (forest/pasture). Nest predation was significantly higher in wet season (42.7%), when no difference was found between edge and forest interior, than in dry season (16.5%), when nest predation was higher in forest interior (400 m). Within seasons, the difference between internal and external edges and the association between edge distance and edge type were not significant. Results suggest that ground nest predation in large protected areas of the Atlantic forest is mainly caused by forest dwellers rather than by species inhabiting the surrounding grassland-dominated landscape, mirroring recent findings in other tropical areas.