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dc.creatorMadden, Kiersten Marie, 1980-en_US
dc.date.accessioned2008-08-29T00:07:56Z
dc.date.available2008-08-29T00:07:56Z
dc.date.created2007-12en_US
dc.date.issued2008-08-29T00:07:56Z
dc.identifier.urihttp://hdl.handle.net/2152/3751
dc.description.abstractDetailed information on diet and foraging behavior is necessary for understanding predator-prey interactions and food-web dynamics. The primary objective of this dissertation was to gain a more complete understanding of the natural foraging behavior of Weddell seals (Leptonychotes weddellii) in McMurdo Sound, Antarctica using a video data recorder to document the seal's three-dimensional movements and encounters with prey. Seals exhibited a variety of dive types that could be sorted into five groups based on 18 dive descriptors. Three of these groups (deep aerobic, deep anaerobic, and shallow aerobic) were identified as foraging dives, the frequency of which varied with bathymetry. Deep aerobic foraging dives were similar in depth and duration to foraging dives in previous studies and were more common at offshore breathing holes. However, differences occurred between offshore free-ranging and isolated-hole dives in the behaviors involving descent and the frequency of certain behavioral transitions. These differences were responses by the seals to variations in prey abundance, rather than responses to a change in breathing hole availability. Even with an apparently homogenous sample of seals, there was significant individual variability in foraging success, behavior, diet, and foraging tactics. Dive depth, duration, distance, and energetic cost were important for explaining foraging success when seals dove in shallow areas where Antarctic silverfish (Pleuragramma antarcticum) were more difficult to reach and less abundant. However, the relationship between those variables was not the same for all individuals. Diet and foraging tactics also varied significantly among individuals diving near the coastline. Two coastal seals specialized on silverfish, while two others consumed silverfish and benthic prey. Although benthic prey were more accessible along the coastline than offshore, silverfish, which have a high lipid content, required less handling to consume. Thus, it may be energy-efficient for seals to specialize on silverfish at coastal locations despite the additional time and energy required to travel to depths where silverfish are located. These results helped us understand variability within Weddell seal populations and the basis upon which foraging decisions are made in response to changes in bathymetry, access to breathing holes, and prey abundance and availability.en_US
dc.format.mediumelectronicen_US
dc.language.isoengen_US
dc.rightsCopyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en_US
dc.subject.lcshWeddell seal--Food--Antarctica--McMurdo Sounden_US
dc.subject.lcshWeddell seal--Locomotion--Antarctica--McMurdo Sounden_US
dc.titleForaging behavior of free-ranging Weddell seals (Leptonychotes weddelli) in the Antarctic fast-ice environmenten_US
dc.description.departmentMarine Science Instituteen_US
dc.identifier.oclc212627917en_US
dc.type.genreThesisen_US
thesis.degree.departmentMarine Science Instituteen_US
thesis.degree.disciplineMarine Scienceen_US
thesis.degree.grantorThe University of Texas at Austinen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US


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