Ke. Omland et Tw. Sherry, PARENTAL CARE AT NESTS OF 2 AGE CLASSES OF MALE AMERICAN REDSTART - IMPLICATIONS FOR FEMALE MATE CHOICE, The Condor, 96(3), 1994, pp. 606-613
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.