Seasonal consistency and individual variation in foraging strategies differ among and within Pygoscelis penguin species in the Antarctic Peninsula region
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Past research during the breeding season in the Antarctic Peninsula region indicates that gentoo penguins (Pygoscelis papua) are generalist foragers whereas Adélie (P. adeliae) and chinstrap (P. antarcticus) penguins tend to specialize on Antarctic krill (Euphausia superba). However, little is known about the degree of temporal consistency in the diets and foraging habitats of these three species, particularly at the individual level. Such year-round and inter-annual dietary understanding is important to help interpret contrasting trends in their populations. We used carbon and nitrogen stable isotope analysis of blood and feathers to evaluate seasonal shifts in diet and individual foraging consistency within Pygoscelis penguin species breeding in the South Shetland Islands as well as among three geographically distinct gentoo penguin populations in the western Antarctic Peninsula and South Shetland Islands. We found that gentoo penguins exhibited a generalist foraging strategy with individual consistency, Adélie penguins exhibited an intermediate generalist foraging strategy with little individual consistency, and chinstrap penguins exhibited a specialized diet with little inter-individual variation. Our results also indicated that all three species have greater variation in foraging habitat use during the post-breeding season compared to the breeding season. Finally, we observed differences in the degree of seasonal shifts in population level diet and consistency in foraging strategies at the individual level across the three gentoo penguin populations examined. This suggests that Pygoscelis penguins can differ in diets and foraging habitat use not only at the population level among species, sites, and seasons, but also in the level of variation within populations, and in the degree of seasonal consistency among individuals.
KeywordsBreeding Season Stable Isotope Analysis Antarctic Peninsula South Shetland Island Antarctic Krill
Many thanks to K. Boysen, P. Chilton, G. Clucas, S. Trivelpiece, A. Will and all field workers who helped to collect the samples used in this study. Funding was provided in part by a NSF Office of Polar Programs grant to S. Emslie and M. Polito (ANT-0739575). We would like to acknowledge support from the Department of Oceanography and Coastal Sciences at Louisiana State University, the CAPES foundation (PDSE scholarship No 6406/2015-07) the Darwin Initiative and public donations during this fieldwork. We also thank the US-AMLR and PROANTAR program, Brazilian Institute INCT-APA, Raytheon Polar Services, Quark Expeditions, the Laurence M. Gould, the M/V Ushuaia, M/V Ocean Diamond for transportation and logistical support. We thank Steve Emslie for assistance with permitting and sample shipping and T. Mauney who provided assistance with sample preparation and stable isotope analysis. We thank Y. Cherel, N. Dehnhard, A. Satake, M. Harvey, and an anonymous reviewer for helpful comments on earlier versions of this manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
Human and animal ethics
Animal use in this study was conducted under approved animal use protocols from the University of North Carolina Wilmington (A0910-20) and Louisiana State University (14-083), the Universidade do Vale do Rio dos Sinos (CNPq: No 574018/2008-5 and FAPERJ: No E-16/170.023/2008), Technology and Innovation (MCTI), of Environment (MMA) and Inter-Ministry Commission for Sea Resources (CIRM) and in accordance to Antarctic Conservation Act permits provided by the U.S. National Science Foundation (NSF) to G. Watters (2011–005) and M. Polito (2015–008).
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