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Marine Ecology Progress Series

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MEPS 519:221-237 (2015)  -  DOI:

Contrasting specialist and generalist patterns facilitate foraging niche partitioning in sympatric populations of Pygoscelis penguins

Michael J. Polito1,*, Wayne Z. Trivelpiece2, William P. Patterson3, Nina J. Karnovsky4, Christian S. Reiss2, Steven D. Emslie5

1Department of Oceanography and Coastal Sciences, Louisiana State University, 1002-Y Energy, Coast & Environment Building, Baton Rouge, Louisiana 70803, USA
2Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service,
8901 La Jolla Shores Drive, La Jolla, California 92037-1508, USA
3Saskatchewan Isotope Laboratory, Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada
4Department of Biology, Pomona College, 175 West 6th Street, Claremont, California 91711, USA
5Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, North Carolina 28403, USA
*Corresponding author:

ABSTRACT: Specialization is a common mechanism of niche differentiation that can lead to ecological co-existence among species. However, species with specialized habitat or dietary requirements often exhibit a high degree of sensitivity to environmental change. Understanding patterns of specialization and niche segregation among Antarctic marine predators is of increased importance because of recent climate-driven reductions in a key prey species, Antarctic krill Euphausia superba. We examined the stomach contents and stable isotope values of sympatric chinstrap Pygoscelis antarctica and gentoo P. papua penguins across 5 breeding seasons at Cape Shirreff, Livingston Island, Antarctica. Our goal was to examine foraging niche segregation and the degree of specialization between species during the chick-rearing period. Dietary and isotopic foraging niches indicated consistent niche partitioning with higher krill consumption and greater use of offshore foraging habitats by chinstrap relative to gentoo penguins. While chinstrap penguin diets were dominated by krill with little variation, gentoo penguins exhibited broader dietary and isotopic niches with a higher degree of variation. There was little evidence that shifts in the availability of adult krill influenced penguin diets or foraging niches during our study, though the contrasting foraging strategies identified provide insight into the differing population trends observed between penguin species. The narrower foraging niche observed in declining chinstrap penguin populations indicates that they are likely highly sensitive to declines in the abundance of Antarctic krill. In contrast, the generalist niche exhibited by recently expanding gentoo penguin populations is likely better suited to the rapidly changing environmental conditions in the Antarctic Peninsula.

KEY WORDS: Stable isotope analysis · Pygoscelis papua · Pygoscelis antarctica · δ13C · δ15N

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Cite this article as: Polito MJ, Trivelpiece WZ, Patterson WP, Karnovsky NJ, Reiss CS, Emslie SD (2015) Contrasting specialist and generalist patterns facilitate foraging niche partitioning in sympatric populations of Pygoscelis penguins. Mar Ecol Prog Ser 519:221-237.

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