There will be winners and losers as climate change alters the habitats of polar organisms. For an Adélie penguin (Pygoscelis adeliae) colony on Beaufort Island (Beaufort), part of a cluster of colonies in the southern Ross Sea, we report a recent population increase in response to increased nesting habitat as glaciers have receded. Emigration rates of birds banded as chicks on Beaufort to colonies on nearby Ross Island decreased after 2005 as available habitat on Beaufort increased, leading to altered dynamics of the metapopulation. Using aerial photography beginning in 1958 and modern satellite imagery, we measured change in area of available nesting habitat and population size of the Beaufort colony. Population size varied with available habitat, and both increased rapidly since the 1990s. In accord with glacial retreat, summer temperatures at nearby McMurdo Station increased by ~0.50°C per decade since the mid-1980s. Although the Ross Sea is likely to be the last ocean with an intact ecosystem, the recent retreat of ice fields at Beaufort that resulted in increased breeding habitat exemplifies a process that has been underway in the Ross Sea during the entire Holocene. Furthermore, our results are in line with predictions that major ice shelves and glaciers will retreat rapidly elsewhere in the Antarctic, potentially leading to increased breeding habitat for Adélie penguins. Results further indicated that satellite imagery may be used to estimate large changes in Adélie penguin populations, facilitating our understanding of metapopulation dynamics and environmental factors that influence regional populations.
Bibliographical noteFunding Information:
Field logistics were provided by the US Antarctic Program, and for the New Zealand team by Antarctica New Zealand, supported by Helicopters NZ and the NZ Defense Force (Squadron 40). We thank C. Kelleher for creating the location map, and J. Pundsack for reviewing previous drafts of this manuscript. The Polar Geospatial Center facilitated the use of imagery for analysis. All penguin survey, capture and handling methods performed during data collection for this study were approved under appropriate ACA permits and by Oregon State University's Institutional Animal Care and Use Committee (ACUP # 3049, 3672, 4130). The use of trade names or products does not constitute endorsement by the U.S. Government.