Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean
During three summer surveys at Prince Edward Island (PEI), southern Indian Ocean (2001, 2004 and 2008), 416 southern elephant seals Mirounga leonina were inspected for identification tags. In all, 42 seals that had been tagged as weaned pups at their natal site were found on Marion Island (MI), 38 o...
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ftjafricanj:oai:ojs.ajol.info:article/49224 2023-05-15T13:37:10+02:00 Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean Oosthuizen, WC Bester, MN de Bruyn, PJN Hofmeyr, GJG 2009-12-18 application/pdf http://www.ajol.info/index.php/ajms/article/view/49224 eng eng NISC http://www.ajol.info/index.php/ajms/article/view/49224/35562 http://www.ajol.info/index.php/ajms/article/view/49224 Copyright for articles published in this journal is retained by the publisher. African Journal of Marine Science; Vol 31, No 3 (2009) 1814-232X info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Peer-reviewed Article 2009 ftjafricanj 2017-03-05T06:46:59Z During three summer surveys at Prince Edward Island (PEI), southern Indian Ocean (2001, 2004 and 2008), 416 southern elephant seals Mirounga leonina were inspected for identification tags. In all, 42 seals that had been tagged as weaned pups at their natal site were found on Marion Island (MI), 38 of which could be individually identified by resighting their tag numbers. The majority of the MI-tagged seals were yearlings or subadults, and all but one were hauled out at PEI for the annual moult. The attendance rate of the known individuals at their natal island during the annual moult was only 40%, based on their resighting histories. This was significantly lower than the 77 ± 6% moult attendance rate estimated for a random MI population sample drawn from the same cohorts (based on 10 000 replications). Annual resight probabilities (considering all haulout phases) was 58% per annum for the MI seals seen at PEI, and 80 ± 4% for the simulation. Seasonal and annual absences of seals from MI violate the ‘homogeneity of capture’ assumption of mark–recapture models. When multiple sightings during any year are treated as a single sighting, resights during other haulouts (e.g. breeding) compensate only partially for absences during the moult. Therefore, mark–recapture studies undertaken in archipelagos should ideally include both marking and resighting of individuals on all islands which will allow discrimination between mortality and local migration. Keywords: capture heterogeneity; dispersal; mark–resight; Mirounga leonina; movement; Prince Edward Islands; site fidelity; sub-AntarcticAfrican Journal of Marine Science 2009, 31(3): 457–462 Article in Journal/Newspaper Antarc* Elephant Seals Marion Island Mirounga leonina Prince Edward Islands Southern Elephant Seals Prince Edward Island AJOL - African Journals Online Indian |
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Open Polar |
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AJOL - African Journals Online |
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ftjafricanj |
language |
English |
description |
During three summer surveys at Prince Edward Island (PEI), southern Indian Ocean (2001, 2004 and 2008), 416 southern elephant seals Mirounga leonina were inspected for identification tags. In all, 42 seals that had been tagged as weaned pups at their natal site were found on Marion Island (MI), 38 of which could be individually identified by resighting their tag numbers. The majority of the MI-tagged seals were yearlings or subadults, and all but one were hauled out at PEI for the annual moult. The attendance rate of the known individuals at their natal island during the annual moult was only 40%, based on their resighting histories. This was significantly lower than the 77 ± 6% moult attendance rate estimated for a random MI population sample drawn from the same cohorts (based on 10 000 replications). Annual resight probabilities (considering all haulout phases) was 58% per annum for the MI seals seen at PEI, and 80 ± 4% for the simulation. Seasonal and annual absences of seals from MI violate the ‘homogeneity of capture’ assumption of mark–recapture models. When multiple sightings during any year are treated as a single sighting, resights during other haulouts (e.g. breeding) compensate only partially for absences during the moult. Therefore, mark–recapture studies undertaken in archipelagos should ideally include both marking and resighting of individuals on all islands which will allow discrimination between mortality and local migration. Keywords: capture heterogeneity; dispersal; mark–resight; Mirounga leonina; movement; Prince Edward Islands; site fidelity; sub-AntarcticAfrican Journal of Marine Science 2009, 31(3): 457–462 |
format |
Article in Journal/Newspaper |
author |
Oosthuizen, WC Bester, MN de Bruyn, PJN Hofmeyr, GJG |
spellingShingle |
Oosthuizen, WC Bester, MN de Bruyn, PJN Hofmeyr, GJG Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean |
author_facet |
Oosthuizen, WC Bester, MN de Bruyn, PJN Hofmeyr, GJG |
author_sort |
Oosthuizen, WC |
title |
Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean |
title_short |
Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean |
title_full |
Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean |
title_fullStr |
Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean |
title_full_unstemmed |
Intra-archipelago moult dispersion of southern elephant seals at the Prince Edward Islands, southern Indian Ocean |
title_sort |
intra-archipelago moult dispersion of southern elephant seals at the prince edward islands, southern indian ocean |
publisher |
NISC |
publishDate |
2009 |
url |
http://www.ajol.info/index.php/ajms/article/view/49224 |
geographic |
Indian |
geographic_facet |
Indian |
genre |
Antarc* Elephant Seals Marion Island Mirounga leonina Prince Edward Islands Southern Elephant Seals Prince Edward Island |
genre_facet |
Antarc* Elephant Seals Marion Island Mirounga leonina Prince Edward Islands Southern Elephant Seals Prince Edward Island |
op_source |
African Journal of Marine Science; Vol 31, No 3 (2009) 1814-232X |
op_relation |
http://www.ajol.info/index.php/ajms/article/view/49224/35562 http://www.ajol.info/index.php/ajms/article/view/49224 |
op_rights |
Copyright for articles published in this journal is retained by the publisher. |
_version_ |
1766088787508592640 |