Mate Choice in Female Northern Orioles with a Consideration of the Role of the Black Male Coloration in Female Choice

In the Northern Oriole (Icterus galbula bullockii), many females visited more than one male before forming a pair bond, but pair formation occurred rapidly, with few displays and little aggression. Most pairs were newly formed each year. Only males advertised for mates, and only males displayed at and chased members of the opposite sex that were not their mates. Females apparently did not discriminate against males whose black coloration had been bleached away. Those bleached males that remained on territory successfully paired and raised young. These results suggest that females do not use the black portion of the male coloration to assess male quality or as an arbitrary badge for female choice. If conspicuous male coloration is important to female mate choice in the Northern Oriole, then mate advertising or invitation-to-promiscuous-copulation may be the function of the coloration.