Early experience affects producer-scrounger foraging tendencies in the house sparrow

Group foragers can use a 'producer' tactic which involves searching for food or a 'scrounger' tactic which involves joining others who have discovered food. While these alternative behaviours are well documented, it is not clear to what extent an individual's tendency to forage independently or to follow others is under genetic control or rather is affected by experience. To examine whether hand-reared juveniles can learn to prefer using a producer or a scrounger tactic, we hand-reared house sparrow, Passer domesticus, nestlings that upon. edging were assigned to one of two training groups; the first was expected to enhance joining ( scrounging) behaviour and the second to enhance searching ( producing) behaviour. In the first group, fledglings were imprinted on a parent model ( stuffed female sparrow) that visited locations containing food. In the second group,fledglings were imprinted on a parent model that visited locations containing no food, while food was available in different locations. At the end of a 5-day training phase, all fledglings were released into a shared aviary, and their social foraging tendencies were measured. We found that fledglings from the first group used significantly more joining behaviour than fledglings from the second group, suggesting that an individual whose early experience positively reinforced joining behaviour is more likely to later become a joiner. To our knowledge, this is the first experimental evidence for the effect of learning on the choice between social foraging strategies in the context of the producere scrounger game. (C) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.