Fledgling begging and parental responsiveness in American dippers (Cinclus mexicanus)

Abstract

In nestling birds, begging typically signals short-term hunger and is often used by parents to allocate food within a brood. Although young birds continue to beg long after nest departure less is known about the information content of begging and its influence on parental allocation patterns post-fledging. We examined the function of begging in fledgling American dippers (Cinclus mexicanus) and the corresponding provisioning rules and response of parents to variation in begging. We found no evidence that begging intensity correlated to short-term hunger. However, fledglings begged at higher intensities in a year with lower food abundance and reduced parental provisioning rates, suggesting that begging may reflect long-term condition. Parental provisioning was influenced by fledgling begging early in the post-fledging period. In the first week after fledging parents preferred to feed the fledgling begging most intensely when choosing between two young, and returned with food more rapidly if fledglings were begging at a higher intensity. In the second week, parents provisioned at a lower rate and no longer adjusted return times in response to variation in fledgling begging intensity. Although the decline in parental responsiveness is consistent with parent-offspring conflict we argue this does not appear to drive the timing of independence in juvenile dippers. © Brill Academic Publishers 2007.