The role of food- and object-sharing in the development of social bonds in juvenile jackdaws (Corvus monedula)

Food sharing in birds occurs largely in the context of parental care and courtship. Previous studies found that juvenile jackdaws demonstrate high levels of active giving outside these contexts in the 3 months following nest dispersal. The function of this behaviour is not understood, although it seemed compatible with hypotheses of mutualism (both participants benefit), reciprocity and harassment avoidance. We propose a new functional explanation for active giving in this species, namely facilitating the formation of social bonds. Captive juvenile jackdaws actively gave 2.5% of temporarily available food items and objects to peers, irrespective of sex and kinship. Active giving accounted for 43.7% of all food transfers. Donors advertised food and objects through a distinctive display and initiated active giving more than recipients. The direction of giving was initially unfocused, but became selective until each donor predominantly gave to one recipient and affiliative relationships were formed. We conclude that food-sharing may be an integral part of jackdaw ontogeny which allows juveniles to explore their social environment and facilitates the formation of affiliative relationships when family bonds dissolve. We also suggest that the ritualised food offer display may signal the 'collaborative intent' of the donor and serve to attract potential partners/mates.