Parental provisioning is weakly age-dependent and heritable in a small passerine

Parental care in birds encompasses many behaviours, from selecting nest-sites and supplying eggs with nutrients to incubation and offspring provisioning. Unlike the early stages, where offspring are passive receivers of care, chicks actively solicit care after hatching. This may lead to either parent–offspring conflict or coadaptation, or both, if there is genetic variance in both parental provisioning and offspring begging. However, given that parental provisioning is highly responsive to brood size and age, its genetic determination is questioned. In this study, we used a multigenerational pedigree and 11 years of provisioning data to dissect the variation in this trait in the Collared Flycatcher Ficedula albicollis, and to examine whether offspring provisioning changes as parents age. We found that the parental provisioning rate was weakly repeatable (r = 0.088–0.213) and heritable (h² = 0.052–0.158). Higher values were obtained when calculated based on within-individual averages rather than individual measurements, and after adjusting for fixed effects. Older parents provisioned offspring at a lower frequency than younger ones. An additive genetic component in provisioning indicates potential for the evolution of parental care, parent–offspring coadaptation and indirect genetic effects on offspring traits. Future studies employing new tracking technologies, including accelerometers, radars and radio-frequency identification readers, may help to determine whether senescence or increased experience causes the lower rate of offspring provisioning observed in older parents.