Analyses of the most abundant marine bird species in the eastern Bering Sea indicate that their distribution and abundance are the result of complex interactions between biotic and abiotic elements of the environment. Of particular importance are the effects of ice systems, food availability, oceanographic frontal systems, and the location of suitable nesting sites. For most species, the southern ice edge acts as a barrier to northward movement in the spring. OCSEAP surveys indicate that previous estimates of seabird populations in the Bering Sea are probably extremely conservative and that more than 40 million seabirds may occupy these marine waters during the summer months.