Pairing in captive brown-headed cowbirds (Molothrus ater)

Abstract

Twenty-five male and 15 female brown-headed cowbirds were captured in the fall of 1966. In mid-December of 1966 they were subjected to extended photoperiod to bring them into breeding condition. Various combinations of yearling and adult males and females were observed in eight trials to determine the effect of age and dominance of males on pairing with females. Both yearling and adult males paired with females. Only dominant males paired with females. Subordinate males remained unpaired if sufficient females were unavailable. These observations confirm impressions formed in field studies on the role of dominance and age in pairing in cowbirds.