Spatial consistency affects foraging effort in a benthic diving seabird, the Black-faced Cormorant

Abstract

For animals which exploit predictable food resources, greater foraging site fidelity has been hypothesized to lead to increased foraging efficiency. However, evidence for this in free-ranging species is limited. In the present study, foraging site fidelity, the factors influencing it and its effect on foraging effort were investigated in the Black-faced Cormorant Phalacrocorax fuscescens, a predominantly benthic forager occurring in southeastern Australia. While the study population was found to have a relatively large foraging range, individuals were highly consistent in the smaller foraging areas which they used. Foraging effort was lower in individuals with a higher foraging site fidelity, which is likely to indicate increased foraging efficiency. Foraging site fidelity differed greatly between individuals but none of the assessed factors (sex, mass, size or year of study) were found to have a significant influence. This might indicate that intrinsic factors which could not be assessed, such as personality or experience, may influence the degree to which individuals exploit known habitats. The findings suggest that changes in prey availability or distribution could result in reduced foraging efficiency and, consequently, negative impacts for the species. Further investigation is required to assess within-individual foraging plasticity to predict potential responses to changing prey availability and distribution.