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Ranging and diving behaviour of adult female southern elephant seals from Marion Island
Dissertation (MSc (Zoology))--University of Pretoria, 1997.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2022
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| _version_ | 1867613591877713920 |
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| access_status_str | Open Access |
| author2 | Bester, Marthan Nieuwoudt |
| author_browse | Bester, Marthan Nieuwoudt |
| author_facet | Bester, Marthan Nieuwoudt |
| collection | Thesis |
| dc_rights_str_mv | © 2021 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Zoology))--University of Pretoria, 1997. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/83243 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:38:35.295Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/83243 Ranging and diving behaviour of adult female southern elephant seals from Marion Island Bester, Marthan Nieuwoudt Jonker, Frans Christiaan UCTD Ranging and diving behaviour adult female southern elephant seals Marion Island Dissertation (MSc (Zoology))--University of Pretoria, 1997. The diving and ranging behaviour of thirteen adult southern elephant seal, Mirounga leonina, post breeding (n = 9) and post moulting (n = 4) females from sub-Antarctic Marion Island (46°54'S 37°45'E) were recorded during their pelagic annual cycling of 1990 - 1994, using Geolocation-Time-depth Recorders. A total of 66 807 dives were categorized into seven distinct types which were hypothesized to serve as functional transit, exploratory and foraging dives. No benthic foraging dives were recorded. Dive depth and duration were positively correlated and both unimodal and bimodal in their frequency distributions. Extended surface intervals were more common during long journeys at sea and were probably associated with successful foraging. It is postulated that the seasonal and individual variation in the diving behaviour of females are related to their geographic locations and the abundance and behaviour of their prey. Movements were categorized into outbound transit, distant foraging and inbound transit phases. The relative frequency of foraging, exploratory and transit dive types, as well as the duration and location of the different phases of movement suggest two clearly different seasonal foraging strategies used by post breeding and post moulting females. Bathymetrical features could possibly provide cues to females at least during part of the journey, to reach distant foraging grounds. Post breeding and post moulting females foraged largely within inter-frontal zones. Diel differences in the depth of hypothesized foraging dives appear to be associated with concentrated foraging on vertically migrating prey. A homogeneous temperature layer at foraging depth seems to cause shifts in the diel patterns of prey dispersal, whereas a heterogeneous temperature layer appears to promote little difference in the diel patterns of migrating prey, thereby causing differences in the diel diving depth of foraging elephant seals. Elephant seals could be using changes in water temperature to predict the presence of prey when foraging at inter-frontal zones, away from readily locatable oceanic features where primary production is known to be high. Zoology and Entomology MSc (Zoology) Unrestricted 2022-01-12T06:00:47Z 2022-01-12T06:00:47Z 19/8/2021 1997 Dissertation * http://hdl.handle.net/2263/83243 en © 2021 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Ranging and diving behaviour adult female southern elephant seals Marion Island Ranging and diving behaviour of adult female southern elephant seals from Marion Island |
| title | Ranging and diving behaviour of adult female southern elephant seals from Marion Island |
| title_full | Ranging and diving behaviour of adult female southern elephant seals from Marion Island |
| title_fullStr | Ranging and diving behaviour of adult female southern elephant seals from Marion Island |
| title_full_unstemmed | Ranging and diving behaviour of adult female southern elephant seals from Marion Island |
| title_short | Ranging and diving behaviour of adult female southern elephant seals from Marion Island |
| title_sort | ranging and diving behaviour of adult female southern elephant seals from marion island |
| topic | UCTD Ranging and diving behaviour adult female southern elephant seals Marion Island |
| url | http://hdl.handle.net/2263/83243 |