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Marine Ecology Progress Series

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MEPS 601:239-251 (2018)  -  DOI:

Post-fledging survival of Adélie penguins at multiple colonies: chicks raised on fish do well

David G. Ainley1,*, Katie M. Dugger2, Mario La Mesa3, Grant Ballard4, Kerry J. Barton5, Scott Jennings2,4,6, Brian J. Karl5, Amelie Lescroël4, Phil O’B. Lyver5, Annie Schmidt4, Peter Wilson5

1H. T. Harvey & Associates Ecological Consultants, Los Gatos, CA 95032, USA
2US Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, USA
3ISMAR-CNR, Istituto di Scienze Marine, UOS di Ancona, 60125 Ancona, Italy
4Point Blue Conservation Science, Petaluma, CA 94954, USA
5Landcare Research, Lincoln 7640, New Zealand
6Present address: ACR, Cypress Grove Research Center, Marshall, CA 94940, USA
*Corresponding author:

ABSTRACT: We assessed whether the mass of Adélie penguin Pygoscelis adeliae fledglings at 3 colonies of markedly disparate size on Ross Island, Ross Sea, correlated with their eventual return as subadults. We compared our results with those from Anvers Island, Bellingshausen Sea. Colony sizes at Ross Island have been increasing, contrary to decreasing size at Anvers Island. At Ross Island, during the month prior to fledging, chick diet consisted equally of energy-dense Antarctic silverfish Pleuragramma antarctica and less-caloric crystal krill Euphausia crystallorophias, while at Anvers Island the diet was principally Antarctic krill E. superba. At Ross Island, the mass of fledglings who subsequently returned (mean ± SE: 3.4 ± 0.0411 kg) exceeded that of those not seen again (3.2 ± 0.0251 kg), compared to Anvers Island (3.2 vs. 3.0 kg, respectively). At Ross Island, fledging mass was inversely related to colony size and, at the largest colony, fledging mass decreased as the colony grew. Average mass of returnees at the largest colony was less than the mass at Anvers Island for those fledglings that did not return. The mean proportion of fish in the chicks’ diet decreased at the largest Ross Island colony over time, as did fledging mass. We hypothesize that intraspecific competition increased along with colony size, decreasing the availability of fish. We further hypothesize that at the large Ross Island colony, post-fledging penguins must be finding adequate prey, and more energy-dense fish, just outside the colony’s foraging area to explain opposing trends in colony trajectories.

KEY WORDS: Adélie penguin · Antarctic silverfish · Anvers Island · Central-place foraging · Ross Island · Intraspecific trophic competition

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Cite this article as: Ainley DG, Dugger KM, La Mesa M, Ballard G and others (2018) Post-fledging survival of Adélie penguins at multiple colonies: chicks raised on fish do well. Mar Ecol Prog Ser 601:239-251.

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