Prefledging mass recession and timing of fledging in Rhinoceros Auklets Cerorhinca monocerata

Abstract

. First, by provisioning older orheavier chicks, the parental gain in fitness through increasedpost-fledging survival of chicks may be smaller than ifthey provisioned younger or lighter chicks. Parents shouldtherefore induce older or heavier chicks to fledge. Secondly,older or heavier chicks are less likely to remain in theirnests during mass recession because their survival pros-pects should be greater away from the nest than theyshould be for younger or lighter chicks.Parental regulation of provisioning according to the ageand growth of the chick is the key assumption of thesehypotheses. However, parental responses to chick age ormass have varied among experiments carried out onAtlantic Puffins