Recent Increase and Southern Expansion of Adelie Penguin Populations in the Ross Sea, Antarctica, Related to Climatic Warming

The numbers of Adelie penguins Pygoscelis adeliae (Hombron and Jacquinot) in the Ross Sea, Antarctica, have increased markedly over the past 10 years. Proportionally, this increase is most pronounced in McMurdo Sound, where the species' breeding range has recently been extended 3 km south to Cape Barne (77- degrees-35'S) with the re-occupation of a former rookery that was abandoned sometime before the present century. These biological trends show remarkable synchronisation with physical evidence of climatic variation in the McMurdo Sound region. We suggest that the dynamics of Adelie penguin populations may be very sensitive indicators of changes in the Antarctic climate.