Patterns of Ovenbird (Seiurus aurocapillus) Pairing Success in Missouri Forest Tracts

Minimum-area-requirement estimates for area-sensitive birds may underestimate the actual area needed to provide long-term breeding habitat because they do not consider the pairing and mating success of territorial males. Patterns of pairing success were studied in Ovenbirds (Seiurus aurocapillus) in north-central Missouri in forest tracts below, approaching, and exceeding minimum-area-requirement estimates for this species. The possible roles of habitat area, isolation, and edge effect in causing reduced pairing success were examined. Male Ovenbird territories were spot mapped within seven forest tracts. Each male was observed to determine if he had acquired a mate. The percentage of paired male Ovenbirds was directly related to forest-tract area and total estimated male Ovenbird population. A higher percentage of males with territories more than 300 m from the forest edge were paired than males with territories less than or equal to 300 m from the forest edge. The combined effect of total forest area, edge-to-interior ratio, and percent forest cover within a 5-km radius of the tracts was highly correlated with pairing success. Edge effects are an important consideration that should be a contributing factor when developing minimum-area-requirement estimates.