Provisioning rates by golden-winged warblers

We studied parental provisioning rates and nestling body condition in an introgressed population of Golden-winged Warblers (Vermivora chrysoptera) in eastern Ontario. Twelve nests were monitored until the young fledged; six nests were parented by phenotypically pure Golden-winged Warbler males and females, and six were parented by pure Golden-winged Warbler males mated with introgressed hybrid females. Nestlings that had a hybrid parent did not show differences in body condition from nestlings with two Golden-winged Warbler parents. Provisioning patterns were examined for potential relationships with several different factors: gender of the parent (male vs. female), nestling age, pair type (pure vs. hybrid), and the proportion of extra-pair young in the brood. Both males and females increased their provisioning rates as nestlings grew, and males consistently provisioned at higher rates than females. Golden-winged Warbler parents and hybrid parents did not show significant differences in provisioning rates. Females significantly increased provisioning rates with increasing levels of extra-pair paternity. Our results suggest that hybrid nestlings are not at a disadvantage in terms of body condition, and that hybrid parents are equally adept at provisioning their young as are phenotypic Golden-winged Warbler parents.