In a crowded environment the natal territory could serve as a haven for young and inexperienced o¡spring until a breeding vacancy emerges. Delayed dispersal and association with kin could then o¡er adaptive bene¢ts through an individual ¢tness gain. Here we report that delayed dispersal is associated with a higher lifetime individual ¢tness in Siberian jay (Perisoreus infaustus) males. Sons bred more successfully and had more reproductive events in life when they delayed dispersal. The higher lifetime reproductive success when sons disperse later in life is su¤cient to promote postponement of natal dispersal, suggesting that dispersal is delayed due to ecological constraints on access to high-quality habitats. We argue that the maintenance of this variation in the timing of dispersal and reproductive success can be reconciled with non-genetic mechanisms driving dispersal. Social dominance within broods re£ecting environmental conditions during growth is such a mechanism.

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