Timing of Offspring Recognition in Adult Starlings

Abstract

1. In the Exchange experiments adult starlings feed a strange brood, introduced at their original nest site up to 16 days post hatch, as frequent as their own young, resulting in a normal weight gain of the strange young. 2. Confronted with a 19 day old alien brood and their own young simultaneously, some adults still occasionally feed the strange young while others are already able to restrict their parental care to their own offspring. 3. Not until the young are aged 20 days or more, the adults arc definitely able to discriminate between own and alien young in the immediate vicinity of the original nesting hole (Choice experiments) or within 10 to 20 m (Search experiments). 4. The experiments altogether show that offspring recognition in Starlings develops only a few days prior to fledging, i.e. by the time the young run the risk of intermingling with other conspecific broods.