Factors influencing predation on Ovenbird (Seiurus aurocapilla) nests in northern hardwoods: Interactions across spatial scales

Microsite, patch, and landscape conditions may interact to influence nest predation. In northern Minnesota, silvicultural and agricultural practices may be involved in recent increases in nest predators and regional declines in several ground-nesting songbirds. To examine this problem, we evaluated 17 hierarchical models of predation on Ovenbird (Seiurus aurocapilla) nests that included microsite variables, distances to edges, and amount of core forest within a 2-km radius surrounding six study plots. During 2000 and 2001, 157 Ovenbird nests were monitored to estimate nest predation rates. A model that included the main effects of litter depth and core forest area and an interaction term between the two best described variation in predation on Ovenbird nests (AIC_c weight = 0.83). The nest predation rate from this model was 0.51 ± 0.01 (mean ± SE), assuming mean values of litter depth and amount of core forest. Shallow litter was associated with higher nest predation in three plots surrounded by less core habitat (40-60 ha), whereas there was no relationship in three plots surrounded by more core area (100-150 ha). Management that promotes deep leaf litter and the maintenance of large, intact forest tracts will likely benefit Ovenbirds and other forest songbirds.