Scaling Patterns in the Foraging Behaviour of Sympatric Plovers: Effects of Body Size and Diet

Abstract

The foraging behaviour of five plover species was studied at Mida Creek, Kenya, to assess how foraging behaviour is influenced by bird body size and/or diet. All five plovers had functionally identical instantaneous foraging behaviour, but the predicted allometric scaling of components of this behaviour with body size was not conclusively demonstrated. Variation in almost all foraging parameters could be better explained by interspecific differences in diet, specifically the relative proportions of prey providing a strong visual cue (e.g. surface-active crabs) versus a weak one (e.g. polychaetes and very small prey). One species, the Greater Sandplover Charadrius leschenaultii, was positioned anomalously in several scaling relationships. If this species was excluded from analyses, six of eight foraging parameters were significantly correlated with body mass. It is not possible to extrapolate the fine details of foraging behaviour from one locality to another and this study strongly suggests that predictions about foraging behaviour based on morphological allometry have limited robustness, even for sympatric species with stereotyped foraging tactics.