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Long-term species, sexual and individual variations in foraging strategies of fur seals revealed by stable isotopes in whiskers

Kernaleguen, Laetitia, Cazelles, Bernard, Arnould, John P. Y., Richard, Pierre, Guinet, Christophe and Cherel, Yves 2012, Long-term species, sexual and individual variations in foraging strategies of fur seals revealed by stable isotopes in whiskers, PLoS one, vol. 7, no. 3, pp. 1-10.

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Title Long-term species, sexual and individual variations in foraging strategies of fur seals revealed by stable isotopes in whiskers
Author(s) Kernaleguen, Laetitia
Cazelles, Bernard
Arnould, John P. Y.
Richard, Pierre
Guinet, Christophe
Cherel, Yves
Journal name PLoS one
Volume number 7
Issue number 3
Start page 1
End page 10
Total pages 10
Publisher Public Library of Science
Place of publication San Francisco, Calif.
Publication date 2012-03-14
ISSN 1932-6203
Keyword(s) arctocephalus-gazella
seasonal-changes
southern-ocean
nitrogen-balance
wavelet analysis
phoca-vitulina
trophic niche
population
specialization
ecology
Summary Background: Individual variations in the use of the species niche are an important component of diversity in trophic interactions. A challenge in testing consistency of individual foraging strategy is the repeated collection of information on the same individuals.

Methodology/Principal Findings: The foraging strategies of sympatric fur seals (Arctocephalus gazella and A. tropicalis) were examined using the stable isotope signature of serially sampled whiskers. Most whiskers exhibited synchronous delta C-13 and delta N-15 oscillations that correspond to the seal annual movements over the long term (up to 8 years). delta C-13 and delta N-15 values were spread over large ranges, with differences between species, sexes and individuals. The main segregating mechanism operates at the spatial scale. Most seals favored foraging in subantarctic waters (where the Crozet Islands are located) where they fed on myctophids. However, A. gazella dispersed in the Antarctic Zone and A. tropicalis more in the subtropics. Gender differences in annual time budget shape the seal movements. Males that do not perform any parental care exhibited large isotopic oscillations reflecting broad annual migrations, while isotopic values of females confined to a limited foraging range during lactation exhibited smaller changes. Limited inter-individual isotopic variations occurred in female seals and in male A. tropicalis. In contrast, male A. gazella showed large inter-individual variations, with some males migrating repeatedly to high-Antarctic waters where they fed on krill, thus meaning that individual specialization occurred over years.

Conclusions/Significance: Whisker isotopic signature yields unique long-term information on individual behaviour that integrates the spatial, trophic and temporal dimensions of the ecological niche. The method allows depicting the entire realized niche of the species, including some of its less well-known components such as age-, sex-, individual- and migration-related changes. It highlights intrapopulation heterogeneity in foraging strategies that could have important implications for likely demographic responses to environmental variability.
Notes This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Language eng
Field of Research 050211 Wildlife and Habitat Management
060201 Behavioural Ecology
060205 Marine and Estuarine Ecology (incl Marine Ichthyology)
Socio Economic Objective 970106 Expanding Knowledge in the Biological Sciences
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2012, Public Library of Science
Persistent URL http://hdl.handle.net/10536/DRO/DU:30046863

Document type: Journal Article
Collections: School of Life and Environmental Sciences
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Every reasonable effort has been made to ensure that permission has been obtained for items included in DRO. If you believe that your rights have been infringed by this repository, please contact drosupport@deakin.edu.au.