HOW MIXED-SPECIES FORAGING FLOCKS DEVELOP IN RESPONSE TO BENEFITS FROM OBSERVATIONAL-LEARNING

We created experimental situations where observers (great tit, Parus m ajor and marsh tit, P, palustris) acquired one of five types of experi ence near conspecific and non-conspecific demonstrators: (1) neither d emonstrator was feeding; (2) only the conspecific was feeding; (3) onl y the non-conspecific was feeding; (4) both were feeding and the obser ver received a reinforcement (food) near the conspecific; and (5) as ( 4), but the reinforcement was given near the non-conspecific. After ea ch treatment, we recorded whether the observer approached a caged cons pecific or a caged non-conspecific. There was a baseline preference fo r approaching conspecifics but this could be overcome by learnt associ ations so that the birds would then approach non-conspecifics. When th ere was an opportunity to distinguish between successful and unsuccess ful foragers (demonstrators), and the successful forager was not consp ecific, observers of the dominant species approached the successful su bordinate non-conspecifics, Observers of the subordinate species appro ached the dominant species only if they had received a food reinforcem ent near them. Observers followed non-conspecific individuals more oft en at temperatures below than above 0 degrees C and chose a conspecifi c individual more often above than below 0 degrees C. (C) 1998 The Ass ociation for the Study of Animal Behaviour.