Diving deeper into individual foraging specializations of a large marine predator, the southern sea lion

Baylis, A. M. M., Orben, R. A., Arnould, J. P. Y., Peters, K., Knox, T., Costa, D. P. and Staniland, I. J. 2015, Diving deeper into individual foraging specializations of a large marine predator, the southern sea lion, Oecologia, vol. 179, no. 4, pp. 1053-1065, doi: 10.1007/s00442-015-3421-4.

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Title Diving deeper into individual foraging specializations of a large marine predator, the southern sea lion
Author(s) Baylis, A. M. M.
Orben, R. A.
Arnould, J. P. Y.ORCID iD for Arnould, J. P. Y. orcid.org/0000-0003-1124-9330
Peters, K.
Knox, T.
Costa, D. P.
Staniland, I. J.
Journal name Oecologia
Volume number 179
Issue number 4
Start page 1053
End page 1065
Total pages 13
Publisher Springer
Place of publication Berlin, Germany
Publication date 2015-12
ISSN 1432-1939
Keyword(s) dietary specialization
habitat selection
hidden Markov models
South American sea lions
state-space models
Summary Despite global declines in the abundance of marine predators, knowledge of foraging ecology, necessary to predict the ecological consequences of large changes in marine predator abundance, remains enigmatic for many species. Given that populations suffering severe declines are of conservation concern, we examined the foraging ecology of southern sea lions (SSL) (Otaria flavescens)-one of the least studied otariids (fur seal and sea lions)-which have declined by over 90 % at the Falkland Islands since the 1930s. Using a combination of biologging devices and stable isotope analysis of vibrissae, we redress major gaps in the knowledge of SSL ecology and quantify patterns of individual specialization. Specifically, we revealed two discrete foraging strategies, these being inshore (coastal) and offshore (outer Patagonian Shelf). The majority of adult female SSL (72 % or n = 21 of 29 SSL) foraged offshore. Adult female SSL that foraged offshore travelled further (92 ± 20 vs. 10 ± 4 km) and dived deeper (75 ± 23 vs. 21 ± 8 m) when compared to those that foraged inshore. Stable isotope analysis revealed long-term fidelity (years) to these discrete foraging habitats. In addition, we found further specialization within the offshore group, with adult female SSL separated into two clusters on the basis of benthic or mixed (benthic and pelagic) dive behavior (benthic dive proportion was 76 ± 9 vs. 51 ± 8 %, respectively). We suggest that foraging specialization in depleted populations such as SSL breeding at the Falkland Islands, are influenced by foraging site fidelity, and could be independent of intraspecific competition. Finally, the behavioral differences we describe are crucial to understanding population-level dynamics, impediments to population recovery, and threats to population persistence.
Language eng
DOI 10.1007/s00442-015-3421-4
Field of Research 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
ERA Research output type C Journal article
Copyright notice ©2016, Springer
Persistent URL http://hdl.handle.net/10536/DRO/DU:30077888

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