Population declines and changes in community composition at the world’s largest penguin colony
Abstract
The Antarctic Peninsula and Scotia Sea are experiencing the greatest pressures from climate change and fisheries in the Southern Ocean, with associated penguin population declines. However, surveys of the South Sandwich Islands in 2011 concluded that numbers there were stable. Zavodovski, the northernmost island in the archipelago, was then hailed as the largest penguin colony in the world. We show that, by 2025, rapid declines of maritime Antarctic chinstrap penguins mean this title has now been ceded to the Adélie penguin colony at Cape Adare, Ross Sea. Over the same period, the subantarctic macaroni penguins increased to become the most abundant species on Zavodovski, representing the largest community shift in Antarctic penguins that has been recorded at a single site. We infer that the most likely primary cause of the chinstrap decline was a reduction in krill availability associated with regional warming, as found across the rest of the Scotia Sea, rather than the volcanic eruption of Zavodovski in 2016 or competition from krill fisheries, macaroni penguins, or humpback whales. The declines of chinstrap penguins mean that reclassification of their global IUCN threat status, from Least Concern to Endangered, requires consideration.
Authors 15
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Norman Ratcliffe corresponding
Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK. Electronic address: notc@bas.ac.uk
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Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
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Affiliation as printed
Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, NY 14850, USA
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Affiliation as printed
Antarctic Research Trust, Am Oste-Hamme-Kanal 10, 27432 Bremervörde, Germany
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Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
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Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
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Affiliation as printed
School of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK
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Affiliation as printed
School of Biological and Medical Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK
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Institute of Geography · University of Edinburgh
Affiliation as printed
School of GeoSciences, Climate Change Research Institute, University of Edinburgh, Edinburgh EH9 3FE, UK
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Nicole Richter Aachen
Affiliation as printed
RWTH Aachen University, Lochnerstr. 4-20, 52056 Aachen, Germany
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Affiliation as printed
Government of South Georgia and South Sandwich Islands, High Cross, Madingley Road, Cambridge CB3 0ET, UK
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Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
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Affiliation as printed
Department of Ecology & Evolution, Stony Brook University, 650 Life Sciences Building, Stony Brook, NY 11794-5245, USA
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Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK; Department of Zoology, University of Johannesburg, Auckland Park, 2092, Johannesburg, South Africa; Millennium Institute, Biodiversity of Antarctic and Sub-Antarctic Ecosystems, 8320150 Santiago, Chile; School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Affiliation as printed
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK