George L. Hunt¹, John P. Croxall² & Richard R. Veit³

Hunt, G.L., Croxall, J.P. & Veit, R.R. 1999. Foraging ecology of marine birds: Selection of foraging habitat by individuals and populations. In: Adams, N.J. & Slotow, R.H. (eds) Proc. 22 Int. Ornithol. Congr., Durban: 2000. Johannesburg: BirdLife South Africa.

Foraging predators should select habitats in which prey are predictably concentrated and available for capture. Selection of foraging habitats is important to marine birds because in many ocean areas prey densities are low and potential prey remain at inaccessible depths. In both the horizontal and vertical dimensions, marine birds focus foraging activities where prey interact with physical processes to produce predictably located concentrations in near-surface waters. Often, activities of sub-surface foragers enhance the surface availability of prey. Differences in wing-loading reflect prey densities and spatial scales at which seabirds forage. Individual birds show preferences for restricted areas of ocean to which they return repeatedly. Seabirds locate foraging areas by observation of other predators, and by olfactory cues in the case of procellariiformes. To investigate habitat selection by foraging seabirds, marine ornithologists have recorded the movements and prey ingestion of instrumented individuals and observed populations in their foraging environments. These observations provide a mechanistic basis for understanding seabird distributions and a means for testing foraging theory.