Female pied flycatchers trade between male quality and mating status in mate choice

According to mate choice theory females should consider both male quality a nd mating status when choosing a mate. In birds, strong experimental eviden ce indicates that females prefer males with elaborate traits. No comparable evidence exists to determine whether females take male mating status into account or how they may trade between male quality and male mating status. We studied mate choice of female pied flycatchers (Ficedula hypoleuca) in o utdoor aviaries where the effect of territory quality could be eliminated a nd where we could control which males were mated and which were unmated. We used male plumage colour as our measure of male quality. In the aviaries, focal females could easily compare males and assess their plumage colour an d mating status, and resident females were prevented from attacking prospec ting females because of separation in different compartments. The study pro vided evidence for a trade-off in mate choice. Females may compromise by ch oosing an already mated male if he is more brightly coloured and, presumabl y, of higher quality than available unmated males. The study did not suppor t the idea that polygyny is based on male deception of females, but the res ults were consistent with the female aggression hypothesis.