PARENTAL CARE AT NESTS OF 2 AGE CLASSES OF MALE AMERICAN REDSTART - IMPLICATIONS FOR FEMALE MATE CHOICE

We compared food provisioning at nests of two age classes of male Amer ican Redstarts (Setophaga ruticilla). Older male redstarts are more li kely to obtain a mate than yearling males. We hypothesized that female s actively choose older males as mates because of direct benefits due to increased rates of nestling provisioning. Lack of foraging experien ce or low food availability on their territories might cause yearling males and their mates to deliver less food to their nestlings. Our res ults did not support this hypothesis. Nestling provisioning rates did not differ between nests of yearling and older males in number of feed ing trips per hour, average load size, estimated mass delivered per ho ur, 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.