PARENTAL CARE AT NESTS OF TWO AGE CLASSES OF MALE AMERICAN REDSTART: IMPLICATIONS FOR FEMALE MATE CHOICE

Abstract

We compared food provisioning at nests of two age classes of male American Redstarts (Setophaga ruticilla). Older male redstarts are more likely to obtain a mate than yearling males. We hypothesized that females actively choose older males as mates because of direct benefits due to increased rates of nestling provisioning. Lack of foraging experience or low food availability on their territories might cause yearling males and their mates to deliver less food to their nestlings. Our results did not support this hypothesis. Nestling provisioning rates did not differ between nests of yearling and older males in number of feeding trips per hour, average load size, estimated mass delivered per hour, nor prey taxa. Direct benefits to the female (at least with regard to nestling provisioning) do not explain why older male redstarts are more likely to obtain a mate. We discuss alternative hypotheses that might explain the lower mating success of yearling male redstarts.