Meeting Abstract
Females often increase reproductive allocation when paired with attractive mates, consistent with the idea that sexually selected traits influence brood value. Similarly, males are predicted to respond to female traits that signal offspring genetic quality or the female’s capacity to contribute parental care. Here, we test the relative influence of a bird’s own and its partner’s traits on parental care in tree swallows (Tachycineta bicolor), a mutually-ornamented species in which plumage color is related to male and female reproductive performance. Using models of avian color vision, we show that both sexes feed offspring at a higher rate when paired with a partner with greener-hued, more female-like plumage. Partner coloration is a better predictor of an individual’s parental behavior than that individual’s own color. Results of a path analysis reveal that offspring of females with greener-hued plumage attain greater mass as a result of additional care provided by their fathers. We suggest that both sexes may benefit by investing more care when paired with a highly invested mate, and that this pattern of differential allocation could contribute to the maintenance of trait variation under selection for bluer-hued, more male-like plumage.
