Sexual and individual foraging segregation in Gentoo penguins Pygoscelis papua from the Southern Ocean during an abnormal winter

• Published in: PLOS ONE
• Main Authors: Xavier, Jose C., Trathan, Philip N., Ceia, Filipe R., Tarling, Geraint A., Adlard, Stacey, Fox, Derren, Edwards, Ewan W.J., Vieira, Rui P., Medeiros, Renata, De Broyer, Claude, Cherel, Yves
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science 2017
• Subjects: Antarctic; Southern Ocean; Austral; Bird Island; Antarc*; Antarctic Krill; Euphausia superba; Pygoscelis papua
• Online Access: http://nora.nerc.ac.uk/id/eprint/516890/; https://nora.nerc.ac.uk/id/eprint/516890/1/Xavier.pdf; https://doi.org/10.1371/journal.pone.0174850

Knowledge about sexual segregation and gender-specific, or indeed individual specialization, in marine organisms has improved considerably in the past decade. In this context, we tested the “Intersexual Competition Hypothesis” for penguins by investigating the feeding ecology of Gentoo penguins during their austral winter non-breeding season. We considered this during unusual environmental conditions (i.e. the year 2009 had observations of high sea surface and air temperatures) in comparison with the long term average at Bird Island, South Georgia. Through conventional (i.e. stomach contents) and stable isotopic values from red blood cells, plasma and feathers of both male and female Gentoo penguins, we showed that there were significant differences between sexes, with males feeding mainly on fish (54% by mass) followed by crustaceans (38%) whereas females fed mainly on crustaceans (89% by mass) followed by fish (4%). Themisto gaudichaudii was the most important crustacean prey for males (64% by mass; 82% by number; 53% by frequency of occurrence) and females (63% by mass; 77% by number; 89% by frequency of occurrence), contrasting with all previous studies that found Antarctic krill Euphausia superba were generally the main prey. Stable isotopic data showed that, in terms of habitat use (based on δ 13C), there were significant differences in short-term carbon signatures between males and females (based on plasma and red blood cells), suggesting that both sexes explored different habitats, with females exploring more offshore pelagic waters and males feeding more in coastal benthic waters. Based on δ 15N, males fed on significantly higher trophic level than females (based on plasma and red blood cells), in agreement with our diet results., Thus, Gentoo penguins behave in a similar manner to other non-breeding penguins species (e.g. king, macaroni and rockhopper penguins), albeit at a smaller spatial scale (as they do not disperse as these other penguins do), in that they have a wider habitat and trophic niche ...