A Distributional Analysis of Diomedea immutabilis and D. nigripes in the North Pacific

Abstract

This is the result of 11 monthly round voyages across the Pacific Ocean between Japan and North America, 1983-85, by means of car-transport ships, granted by Toyota Foundation. All the seabird species were censused and their distributional patterns were analysed, of which the comparative distributional analysis of two albatrosses, the Laysan Diomedea immutabilis and the Black-footed D. nigripes are presented here. The former species outnumbered the latter in total counts, but showed clumped patterns in some sea areas, particularly in NW Pacific, while the latter species was more evenly distributed in low densities, particularly in the SE Pacific between Hawaii and U. S. coast. Factors responsible for this were not definitely proved, but the need of future research on food preference, or segregation, is suggested.