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Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds

Most competition studies between species are conducted from a population-level approach. Few studies have examined inter-specific competition in conjunction with intra-specific competition, with an individual-based approach. To our knowledge, none has been conducted on marine top predators. Sympatri...

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Autores principales: Villegas-Amtmann, Stella, Jeglinski, Jana W. E., Costa, Daniel P., Robinson, Patrick W., Trillmich, Fritz
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744541/
https://www.ncbi.nlm.nih.gov/pubmed/23967096
http://dx.doi.org/10.1371/journal.pone.0070748
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author Villegas-Amtmann, Stella
Jeglinski, Jana W. E.
Costa, Daniel P.
Robinson, Patrick W.
Trillmich, Fritz
author_facet Villegas-Amtmann, Stella
Jeglinski, Jana W. E.
Costa, Daniel P.
Robinson, Patrick W.
Trillmich, Fritz
author_sort Villegas-Amtmann, Stella
collection PubMed
description Most competition studies between species are conducted from a population-level approach. Few studies have examined inter-specific competition in conjunction with intra-specific competition, with an individual-based approach. To our knowledge, none has been conducted on marine top predators. Sympatric Galapagos fur seals (Arctocephalus galapagoensis) and sea lions (Zalophus wollebaeki) share similar geographic habitats and potentially compete. We studied their foraging niche overlap at Cabo Douglas, Fernandina Island from simultaneously collected dive and movement data to examine spatial and temporal inter- and intra-specific competition. Sea lions exhibited 3 foraging strategies (shallow, intermediate and deep) indicating intra-specific competition. Fur seals exhibited one foraging strategy, diving predominantly at night, between 0–80 m depth and mostly at 19–22 h. Most sea lion dives also occurred at night (63%), between 0–40 m, within fur seals' diving depth range. 34% of sea lions night dives occurred at 19–22 h, when fur seals dived the most, but most of them occurred at dawn and dusk, when fur seals exhibited the least amount of dives. Fur seals and sea lions foraging behavior overlapped at 19 and 21 h between 0–30 m depths. Sea lions from the deep diving strategy exhibited the greatest foraging overlap with fur seals, in time (19 h), depth during overlapping time (21–24 m), and foraging range (37.7%). Fur seals foraging range was larger. Cabo Douglas northwest coastal area, region of highest diving density, is a foraging “hot spot” for both species. Fur seals and sea lions foraging niche overlap occurred, but segregation also occurred; fur seals primarily dived at night, while sea lions exhibited night and day diving. Both species exploited depths and areas exclusive to their species. Niche breadth generally increases with environmental uncertainty and decreased productivity. Potential competition between these species could be greater during warmer periods when prey availability is reduced.
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spelling pubmed-37445412013-08-21 Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds Villegas-Amtmann, Stella Jeglinski, Jana W. E. Costa, Daniel P. Robinson, Patrick W. Trillmich, Fritz PLoS One Research Article Most competition studies between species are conducted from a population-level approach. Few studies have examined inter-specific competition in conjunction with intra-specific competition, with an individual-based approach. To our knowledge, none has been conducted on marine top predators. Sympatric Galapagos fur seals (Arctocephalus galapagoensis) and sea lions (Zalophus wollebaeki) share similar geographic habitats and potentially compete. We studied their foraging niche overlap at Cabo Douglas, Fernandina Island from simultaneously collected dive and movement data to examine spatial and temporal inter- and intra-specific competition. Sea lions exhibited 3 foraging strategies (shallow, intermediate and deep) indicating intra-specific competition. Fur seals exhibited one foraging strategy, diving predominantly at night, between 0–80 m depth and mostly at 19–22 h. Most sea lion dives also occurred at night (63%), between 0–40 m, within fur seals' diving depth range. 34% of sea lions night dives occurred at 19–22 h, when fur seals dived the most, but most of them occurred at dawn and dusk, when fur seals exhibited the least amount of dives. Fur seals and sea lions foraging behavior overlapped at 19 and 21 h between 0–30 m depths. Sea lions from the deep diving strategy exhibited the greatest foraging overlap with fur seals, in time (19 h), depth during overlapping time (21–24 m), and foraging range (37.7%). Fur seals foraging range was larger. Cabo Douglas northwest coastal area, region of highest diving density, is a foraging “hot spot” for both species. Fur seals and sea lions foraging niche overlap occurred, but segregation also occurred; fur seals primarily dived at night, while sea lions exhibited night and day diving. Both species exploited depths and areas exclusive to their species. Niche breadth generally increases with environmental uncertainty and decreased productivity. Potential competition between these species could be greater during warmer periods when prey availability is reduced. Public Library of Science 2013-08-15 /pmc/articles/PMC3744541/ /pubmed/23967096 http://dx.doi.org/10.1371/journal.pone.0070748 Text en © 2013 Villegas-Amtmann et al http://creativecommons.org/licenses/by/4.0/ 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 properly credited.
spellingShingle Research Article
Villegas-Amtmann, Stella
Jeglinski, Jana W. E.
Costa, Daniel P.
Robinson, Patrick W.
Trillmich, Fritz
Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds
title Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds
title_full Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds
title_fullStr Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds
title_full_unstemmed Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds
title_short Individual Foraging Strategies Reveal Niche Overlap between Endangered Galapagos Pinnipeds
title_sort individual foraging strategies reveal niche overlap between endangered galapagos pinnipeds
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744541/
https://www.ncbi.nlm.nih.gov/pubmed/23967096
http://dx.doi.org/10.1371/journal.pone.0070748
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