How mixed-species foraging flocks develop in response to benefits from observational learning

We created experimental situations where observers (great tit,Parus majorand marsh tit,P.palustris) acquired one of five types of experience near conspecific and non-conspecific demonstrators: (1) neither demonstrator was feeding; (2) only the conspecific was feeding; (3) only the non-conspecific was feeding; (4) both were feeding and the observer received a reinforcement (food) near the conspecific; and (5) as (4), but the reinforcement was given near the non-conspecific. After each treatment, we recorded whether the observer approached a caged conspecific or a caged non-conspecific. There was a baseline preference for approaching conspecifics but this could be overcome by learnt associations so that the birds would then approach non-conspecifics. When there was an opportunity to distinguish between successful and unsuccessful foragers (demonstrators), and the successful forager was not conspecific, observers of the dominant species approached the successful subordinate non-conspecifics. Observers of the subordinate species approached the dominant species only if they had received a food reinforcement near them. Observers followed non-conspecific individuals more often at temperatures below than above 0°C and chose a conspecific individual more often above than below 0°C.