INDIVIDUAL FEEDING SPECIALIZATIONS OF WINTERING TURNSTONE ARENARIA-INTERPRES

On a rocky shore in SE Scotland wintering turnstone used 6 techniques to obtain prey: routing (flicking and bulldozing seaweed aside), probing, stone-turning, hammer-probing, digging and surface pecking. There were significant individual differences in the use of these techniques both between and within flocks of stable membership: several individuals specialized in the use of particular techniques and all displayed varying degrees of predilection for each technique. Individuals' predilections remained the same between 2 winters. Individual phenotypic differences had highly significant effects on the use of feeding techniques in all flocks, as did microhabitat, probably because certain techniques could only be used or were more profitably used in certain microhabitats. Season and tide were important when interacting with other variables, particularly microhabitat. The strongest effect of sex on feeding behaviour occurred when the only 2 viable techniques were probing and stone-turning: females turned over stones more often than did males. In all flocks an effect of status occurred invariably where the 2 possible techniques that could be used were routing and probing: high status birds routed more often than did low status birds. -from Author