Variation in foraging behavior among nesting stages of female Red-faced Warblers

Abstract

Foraging rates and maneuvers were examined in breeding female Red-faced Warblers (Cardellina rubrifrons) among egg-laying, incubation, and nestling stages. All measures varied among nesting stages, with prey attack rate and search speed significantly increasing from egg-laying to incubation through the nestling stage. During egg-laying and incubation, birds gleaned stationary prey from a fixed perch, but shifted to hover-sallying for stationary prey during the nestling period. These dynamic behavioral patterns may reflect responses to variable time constraints and energetic costs associated with different stages of the nesting cycle.