Attractive males provide less parental care in two populations of the common yellowthroat

Male ornaments may be signals of direct or indirect benefits to females that mate with those males. One important direct benefit to females is the level of male parental assistance they receive when provisioning young. Three main hypotheses attempt to explain the relationship between male ornament size and parental care. The good parent hypothesis predicts that males with larger ornaments will provide more care, while the differential allocation and trade-off hypotheses predict that they will provide less care. We examined the relationship between male ornamentation and parental care in two populations of common yellowthroats, Geothlypis trichas, in which the sexually selected male ornament differs. More ornamented males provided less parental care in both populations, contrary to the good parent hypothesis. However, females did not feed their nestlings more frequently when mated with more ornamented males, which is an additional prediction of the differential allocation hypothesis. Our results are most consistent with the trade-off hypothesis, which suggests that more ornamented males provide less care because they spend relatively more of their effort in pursuing extrapair mates or defending their territories from other males.