Factors Affecting Feeding and Brooding of Gray Catbird Nestlings

Abstract

Gray catbirds (D. carolinensis) were studied to document patterns of feeding and brooding nestlings and to relate these to nestling age, brood size, time of day, time of season and weather. Major factors affecting feeding were nestling age and brood size. The average number of food deliveries .cntdot. brood-1 .cntdot. h-1 increased linearly with the log of nestling age for male and female parents. Volume of food delivered per feeding trip increased linearly with nestling age. As brood size increased, feeding frequencies per brood increased but food deliveries per nestling decreased. Brooding and shading were affected mainly by nestling age and ambient temperature. Time spent brooding decreased substantially as nestlings grew older. Shading was important when the sun shone directly on the nest. Females spent significantly more time brooding nestlings when rain increased. As ambient temperature increased, time spent shading increased and time spent brooding declined.