Parent presence, delayed dispersal, and territory acquisition in the Seychelles warbler

The presence of parents in the natal territory may play an important, but often overlooked, role in natal dispersal and the consequent acquisition of a territory. Living with parents in a territory may confer a fitness advantage to subordinates through, for example, the nepotistic behavior of the parents or indirect benefits gained by helping to raise nondescendent kin. When a parent is replaced by a stepparent, such advantages are reduced or disappear and, as a result, subordinates may disperse. Subordinates that disperse after parent replacement may be constrained in their timing of dispersal, which could have negative fitness consequences. In the cooperatively breeding Seychelles warbler, we show that when a parent was naturally replaced or experimentally removed and subsequently replaced by a stepparent from outside the territory, subordinates were more likely to disperse than when both parents remained in the natal territory. Furthermore, subordinates dispersing from territories in which one or both parents had been replaced were less likely to acquire a breeder position than subordinates dispersing when both parents were still on the natal territory. Our findings suggest that the presence of parents in the natal territory may promote delayed dispersal and facilitate the eventual acquisition of a breeder position outside the natal territory. Our results support the idea that the prolonged parental care, which long-lived species are able to provide, may have selected for family living. Copyright 2007, Oxford University Press.