Foraging behavior predicts age at independence in juvenile Eurasian dippers (Cinclus cinclus)

Timing of foraging independence may be controlled by parents,offspiing, or both and may have consequences for dispersal,reproduction, and survival In a study of juvenile Eurasian dippers(Cinclus cinchus), I examined the relationship between individualdifferences in parental provisioning, the development of foraging,and the timing of independence. Young dippers forage very differentlyfrom adults, specializing on small, stationary pre such as simuliidlarvae (Diptera), and avoiding energetically costly and highlyskilled foraging techniques, such as diving, by which adultsobtain larger prey In my Welsh study area, age at independencevaried substantially within and between broods. Juveniles thatrelied more on simuliids and less on larger prey were independentsooner, as were juveniles with higher rates of intake whileforaging the effect was obvious 3–4 days after fledging.Provisioning rate and total caloric intake over the dependentperiod was unrelated to age at independence, although greaterreliance on parental feeding was associated with higher totalcaloric intake. Higher rates of intake from begging were correlatedwith reduced foraging time. The results demonstrate that theacquisition of the adult foraging strategy is not a prerequisitefor independence or, hence, dispersal. In fact, mastering theskills necessary to capture larger prey may delay independence.Individual juvenile dippers seem to find different solutionsto the trade-off between gaining sufficient food (either frombegging or from foraging for simuliids) and the eventual necessityof learning to forage like an adult.