Sabine's Gull (<i>Xema sabini</i>), Ross's Gull (<i>Rhodostethia rosea</i>) and Ivory Gull (<i>Pagophila eburnea</i>) Gulls in the Arctic: A Review

The earliest information on Sabine's gull, Ross's gull and Ivory gull was collected by several heroic arctic explorers during the nineteenth century and the beginning of the twentieth. Ross's gull was discovered in northern Canada in 1823 by James C. Ross and Sabine's gull in northwestern Greenland in 1818 by Edward Sabine. S.A. Buturlin was the first to find the breeding places of Ross's gull in northeastern Siberia. Recently new breeding places have been reported from U.S.S.R. (Taymyr Peninsula, 1973), Canada (near Devon Island, 1976 and 1978; near Churchill, Manitoba, 1980) and Greenland (Peary Land and Disko Bay, 1979). Sabine's gull and Ivory gull have a dispersed and patchy distribution with gaps too wide for them to be regarded as true continuous circumpolar species. The biotope requirements for the three species are compared. All three are food opportunists; recent data on their food choice and foraging behaviour are reviewed and discussed. The breeding ecology of the gulls is updated with special attention to the clutch size, where a climatological trend may be distinguished. In contrast to birds in general, the most southerly breeding species (Ross's gull) has the largest clutch size and the most northerly breeding species (Ivory gull) has the smallest. Details of the large interspecific differences in migratory and wintering habits are presented. The documented northbound autumn migration of Ross's gull observed in Alaska and the southbound migration of Sabine's gull to western South America and southwestern and southern Africaare surveyed. The Ivory gull is regarded as a straggler during the winter, but recent observations on East Greenland of at least 500 migrating birds in September 1975 indicate that specific migratory routes may be used by this species too.