MEPS 206:297-309 (2000)  -  doi:10.3354/meps206297

ABSTRACT: Feeding by piscivorous marine seabirds necessitates some spatial association between them and their prey. Many attempts have been made to establish spatial associations between seabirds and their prey, yet small-scale (<1 km) proximate association is rarely found. In this paper, we review past attempts to examine spatial proximity, and provide yet another attempt which introduces the concept of a feeding cluster or association of birds. We show, using data collected on acoustic surveys in the neighborhood of the Pribilof Islands, Alaska, during September 1994 to 1997, that larger clusters (>10 birds) of piscivorous murres (Uria spp.) and puffins (Fratercula spp.) are consistently associated with their major prey in this area, large shoals of Age-0 pollock Theragra chalcogramma. Furthermore, the number of birds in a bird cluster is usually proportional to the biomass of fish under that cluster.

KEY WORDS: Spatial association · Bird clusters