PATTERNS OF OVENBIRD (SEIURUS-AUROCAPILLUS) PAIRING SUCCESS IN MISSOURI FOREST TRACTS

Minimum-area-requirement estimates for area-sensitive birds may undere stimate the actual area needed to provide long-term breeding habitat b ecause they do not consider the pairing and mating success of territor ial males. Patterns of pairing success were studied in Ovenbirds (Seiu rus aurocapillus) in north-central Missouri in forest tracts below, ap proaching, and exceeding minimum-area-requirement estimates for this s pecies. The possible roles of habitat area, isolation, and edge effect in causing reduced pairing success were examined. Male Ovenbird terri tories were spot mapped within seven forest tracts. Each male was obse rved to determine if he had acquired a mate. The percentage of paired male Ovenbirds was directly related to forest-tract area and total est imated male Ovenbird population. A higher percentage of males with ter ritories more than 300 m from the forest edge were paired than males w ith territories less than or equal to 300 m from the forest edge. The combined effect of total forest area, edge-to-interior ratio, and perc ent forest cover within a 5-km radius of the tracts was highly correla ted with pairing success. Edge effects are an important consideration that should be a contributing factor when developing minimum-area-requ irement estimates.