PUBLIC INFORMATION CUES AFFECT THE SCROUNGING DECISIONS OF STARLINGS

The foraging decisions that individuals make within groups should depe nd on the information available to them. An aviary experiment was cond ucted to examine whether a starling's, Sturnus vulgaris, decisions eit her to approach and feed from (scrounge) or to avoid the patches explo ited by a partner bird are influenced by the information the partner p rovides. Both the type of information a subject could recognize and th e point at which this information became available during the partner' s exploitation of a patch were manipulated. Information concerning the quality of a patch was available in the form of a concealed colour cu e and from the behaviour of the partner bird. The foraging environment was manipulated such that colour cues were either present or absent, and provided either correct or incorrect information concerning the pr esence of food. When cues corresponded with past foraging experience, test subjects responded selectively and profitably to the patch exploi tations of the partner; they scrounged from a higher proportion of pro fitable patches than control birds, which lacked the ability to recogn ize colour cues. Test subjects also arrived more quickly at profitable patches that the partner bird discovered than did control birds; and consequently, were able to obtain more food at each food patch scroung ed. Finally, test subjects avoided scrounging when the partner discove red empty patches and thus saved foraging time. Responding selectively to public information, therefore, allows an individual to compete mor e effectively for resources within a foraging group.