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Marine Ecology Progress Series

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MEPS 645:205-218 (2020)  -  DOI:

Diet segregation in Adélie penguins: some individuals attempt to overcome colony-induced and annual foraging challenges

Melanie Massaro1,*, David G. Ainley2, Jarrod A. Santora2, 3, 4, Petra Quillfeldt5, Amélie Lescroël6, Amy Whitehead7, Arvind Varsani8, Grant Ballard6, Phil O’B. Lyver9

1School of Environmental Sciences, Institute for Land, Water and Society, Charles Sturt University, Albury, NSW 2640, Australia
2H. T. Harvey & Associates, Los Gatos, CA 95032, USA
3Department of Applied Mathematics, University of California, Santa Cruz, Santa Cruz, CA 95060, USA
4Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 110 McAllister Way, Santa Cruz, CA 95060, USA
5Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Heinrich-Buff Ring, 35392 Giessen, Germany
6Point Blue Conservation Science, Petaluma, CA 94954, USA
7National Institute of Water and Atmospheric Research, PO Box 8602, Christchurch 8440, New Zealand
8The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life sciences, Arizona State University, Tempe, AZ 85287, USA
9Manaaki Whenua Landcare Research, PO Box 69040, Lincoln 7640, New Zealand
*Corresponding author:

ABSTRACT: Intraspecific competition for food can be especially high in colonial breeding seabirds. To minimize colony-induced or annual foraging challenges, diet may vary among individuals, but few studies have simultaneously investigated the effects of both extrinsic conditions (e.g. colony or year effects) and parameters of an individual (e.g. sex, age or individual quality) on diet in seabirds. Using stable isotope analyses, we studied the diet of 214 Adélie penguins Pygoscelis adeliae of known sex, age and breeding quality, nesting in 2 colonies on Ross Island, Antarctica, over 3 breeding seasons. During the study, δ15N and δ13C isotope values were lower in penguins breeding at Cape Crozier compared to those at Cape Bird, revealing a difference in prey proportions. Cape Bird penguins were estimated to consistently consume more energy-rich silverfish Pleuragramma antarctica, while birds at Cape Crozier ate more crystal krill Euphausia crystallorophias. We also found inter-annual differences in diet, with a higher dietary fish proportion in both colonies during 2011. Males had significantly higher δ15N values, indicating a higher fish consumption than females. This sexual segregation in diet was particularly pronounced at Cape Bird, where the overall isotopic niche was wider than at Cape Crozier. Differences in diet among adults of varying ages only existed at Cape Bird, where middle-aged penguins consumed more fish than old and young penguins. This study provides evidence that Adélie penguin diet is largely driven by annual, seasonal and local abundances of prey, with only some individuals selectively foraging for more nutritional prey if prey choices are present.

KEY WORDS: Adélie penguin · Crystal krill · Diet segregation · Intraspecific competition · Ross Sea · Silverfish

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Cite this article as: Massaro M, Ainley DG, Santora JA, Quillfeldt P and others (2020) Diet segregation in Adélie penguins: some individuals attempt to overcome colony-induced and annual foraging challenges. Mar Ecol Prog Ser 645:205-218.

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