Effects of forest edges on ovenbird demography in a managed forest landscape

We studied the reproductive ecology of Ovenbirds (Seiurus aurocapillus) for 3 years in a primarily forested landscape in northern Wisconsin. We searched for and monitored nests in large, closed-canopy northern hardwood forests adjacent to recent clearcuts ( 1) for Ovenbirds in the landscape we studied. Our assessment of population status, however, was extremely sensitive to variation in survival estimates. We used geographic information system data from the Nicolet National Forest to estimate population size in northern and mixed-hardwood forests in this region and to quantify annual productivity in this landscape. Ovenbirds near forest edges faced higher predation pressure but laid more eggs on average than birds in the forest interior. Our data suggest that Ovenbirds may make tradeoffs between the probability of nest success and the per-nest productivity as measured by clutch size. Our findings are consistent with the equilibrium state of the ideal free distribution model in that although individual demographic characteristics (nest success and clutch size) varied with distance from edge, an important correlate of fitness, finite rate of increase (λ) remained relatively similar.