The ornithology of the Ross Sea

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Abstract
Knowledge of the recent history of antarctic glaciation, sea-ice cover and temperatures suggests that the Ross Sea area has been habitable by birds for some 10,000 years. However, the glaciers in McMurdo Sound precluded colonisation there until about 6,000 yr B.P. Relative sea-level changes would ensure that the full history of penguin occupation has been preserved in antarctic sites but that breeding places on subantarctic and ternperatre shores during the ice-age maxima have been inundated. There is a steady fall-off in numbers of breeding species towards the antarctic mainland. There are 31 species in the antarctic region, 12 of which occur on the continent. Only three species are known to breed about McMurdo Sound. Antarctic species have close relatives in subantarctic and temperate regions. Adélie penguins breed at 26 or 27 sites in the region. There are six sites on. the Balleny Islands, 12 or 13 on Victoria Land and eight on the southern volcanic islands. It is estimated that in total there are between 0.5 million to 0.75 million breeding birds. Emperor penguins breed at six sites and total approximately 44,000 breeding pairs. Surveys are inadequate for the other species. The major proportion of the population of penguins and skuas is prebreeding and would not be enumerated in counts made at breeding sites. It is estimated that the total number of birds associated with each breeding site is approximately five times the breeding numbers. Intensive work over the past decades has provided a very substantial literature for most aspects of penguin and skua biology but little has been accomplished for petrels. Most studies have been of short to medium duration. A long-term demographic study of known age birds has been carried out at Cape Crozier. Only asmall amount of research has considered topics of a broader interest than the biology and adaptation of birds to this special environment.