Bringing Home the Bacon: Potential Energy Return from Prey and Central Place Foraging in a Willie Wagtail Rhipidura leucophrys

Abstract

Many insectivorous birds with dependent young are ‘single prey loaders’, capturing a single prey before returning to a central location to feed their young (central place foraging or CPF, see Stephens & Krebs 1986). Given the energetic costs in carrying prey to a central place, one important prediction of CPF is that large prey should be transported and small prey eaten on the spot (Korpimaki et al. 1994). Here, we report observations relevant to this prediction made on a breeding Willie Wagtail Rhipidura leucophrys feeding on grasshoppers Acrida conica (Orthoptera: Acrididae). By observing one prey species in detail we were able to note not only which prey instars were carried to the dependent young, but also to record the handling times for the parent bird feeding on particular prey instars itself and hence determine the most energetically rewarding prey size for the parent to eat itself rather than transport to the young.