Aspects of foraging in black oystercatchers (Aves: Haematopodidae)

I studied foraging ecology of black oystercatchers (Haematopus bachmani) in the rocky intertidal. The aims of this study were: 1) to analyze prey choice and patch choice by adult black oystercatchers and evaluate how well their foraging performance was predicted by foraging theory; 2) to study development of foraging in young oystercatchers; 3) to indirectly examine the relationship between parental foraging performance and fitness by measuring chick growth and chick production. The following conclusions were reached: 1) Prey selection by oystercatchers was generally as predicted by theory, but birds showed partial preferences for prey. Patch choice followed general theoretical predictions, but profitabilities achieved within particular patch types were highly variable. Reasons for this are discussed. 2) Growth and physical maturation are important components in development of foraging. During the period of this study, chicks were heavily dependent on parental feeding, and the ability of chicks to forage independently developed after chicks left their natal area at about 50 days of age. 3) Chick growth varied between one-chick and two-chick broods, and this may be related to parental foraging performance. However, during this study chick production was constrained by weather and predation, and no relationship between parental foraging performance and fitness could be defined.Science, Faculty ofZoology, Department ofGraduat