SELFISH LONG-TERM BENEFITS OF HOARDING IN THE SIBERIAN JAY

We followed the consumption of cached food in Siberian jay flocks duri ng winter. Siberian jay flocks contain kin associations composed of pa rents in company with mature offspring. Further, flocks often contain immigrants not closely related to the group members. We studied the ex tent to which Siberian jay offspring kept caches to themselves or whet her they showed a kin bias and shared cached food mutualistically with relatives (parents/siblings) thus making an inclusive fitness gain. W e recorded the retrieval of cached food using radio-ptilochronology, a technique that detects the consumption of a radioactively labeled foo d item in the growth bar laid down in a growing feather the day of con sumption. Food caching entailed a selfish benefit to the hoarder. The hoarding bird showed a substantial ''recovery advantage'' and retrieve d its own cached food seven times as often as any of its flock mates. There was no evidence for mutualistic sharing of caches among relative s. This selfish benefit persisted throughout the 7-week period for whi ch we could follow the consumption of labeled food.