Selfish long-term benefits of hoarding in the Siberian jay

Abstract

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