Trends in the Breeding Population of Adélie Penguins in the Ross Sea, 1981–2012: A Coincidence of Climate and Resource Extraction Effects

• DOI: 10.1371/journal.pone.0091188
• Publication Date: 2014-03-12T16:38:34Z
• Authors: Phil O’B. Lyver; Mandy Barron; Kerry J. Barton; David G. Ainley; Annie Pollard; Shulamit Gordon; Stephen McNeill; Grant Ballard; Peter R. Wilson
• Keywords: Pygoscelis; Metapopulation; Breeding pair

Measurements of the size Adélie penguin (Pygoscelis adeliae) colonies southern Ross Sea are among longest biologic time series in Antarctic. We present an assessment recent annual variation and trends abundance growth rates these colonies, adding to published record not updated for more than two decades. High angle oblique aerial photographic surveys were acquired penguins counted breeding seasons 1981–2012. In last four years numbers Beaufort Island (southern metapopulation) reached their highest levels since counts began 1981. Results indicated that 855,625 pairs established territories western Sea, with just over a quarter (28%) those portion, constituting semi-isolated metapopulation (three on Island, one nearby Island). The population had negative per capita rate −0.019 during 1981–2000, followed by positive 0.067 2001–2012. Colony this showed striking synchrony through time, indicating large-scale factors influenced growth. contrast increased colony sizes population, patterns change northern difficult characterize. Trends similar until mid-1990s, after which signal was lost owing significantly reduced frequency surveys. Both climate recovery whale populations likely played roles 2000, depletion another trophic competitor, Antarctic toothfish (Dissostichus mawsoni), may explain sharp increasing trend evident then.