Male ornamentation, timing of breeding, and cost of polygyny in the collared flycatcher

Highly ornamented males are often thought to be better able to provide females with resources, parental assistance, or good genes. Individual variation in such male abilities may override the costs of polygyny and therefore largely explain within-population variation in mating patterns. We investigated the influence of variation in male ornamentation and the environment on the costs of polygyny for female collared flycatchers (Ficedula albicollis), using data from a long-term study involving 2733 breeding attempts over 19 years. We show that females suffer reduced reproductive success when mated polygynously but that the costs of polygyny depend on an interaction between male ornamentation and timing of breeding. Among early breeders, polygynously mated females experience higher reproductive success when mated to less ornamented males, but among late breeders, females mated polygynously to highly ornamented males were more successful. We suggest that a high effort spent on obtaining extrapair matings early in the season renders highly ornamented males less able to assist two females in caring for the young. Thus, a male's ability to simultaneously gain from extrapair matings and polygyny may be limited through direct effects on female reproductive success. Given such limitation, extrapair matings may be expected to be less frequent in species with biparental care and a high level of social polygyny. Copyright 2003.