Parent-offspring conflict over duration of parental care and its consequences in tawny owls Strix aluco

摘要

In species defending territories, fitness of newly independent juveniles could depend on phenotypic quality or early access to vacant resources as a result of rapid dispersal. In the first case, parent-offspring conflict will arise when parents cease feeding maturing offspring while these still demand provisioning. In the latter case, the young should decide when to stop begging to search for vacant territories. I radio-tracked 72 juvenile tawny owls from independence to sexual maturity to investigate whether parents or offspring decided the timing of the onset of independence and compare effects of age versus date of independence on survival and reproductive status. Juvenile owls stopped begging when 90-123 d old. This was synchronous within broods, independent of gender or age rank. Independence age of cross-fostered young varied across foster nests but was independent of hatching nest. After independence, young roosted in their parents' territory for 18 d on average before dispersal. This suggests that juvenile owls would rather extend dependency than disperse early. As predicted from this behaviour, age of independence had a positive influence on survival and reproductive status at maturity, whereas there were no effects of date of independence.