Aspects of the ecology of killer whale (Orcinus orca Linn.) groups in the near-shore waters of Sub-Antarctic Macquarie Island

Show simple item record Travers, Toby Van den Hoff, John Lea, Mary-Anne Carlyon, Kris Reisinger, Ryan Rudolf De Bruyn, P.J. Nico Morrice, Margie 2018-07-27T10:12:22Z 2018-11
dc.description.abstract Occurrences of killer whales (Orcinus orca) in the waters surrounding Sub-Antarctic Macquarie Island have been recorded since the 1820s; however, their presence only became the focus of scientific research in the mid-1990s. The analyses of sightings data collected from the island between 1986 and 2015 are presented herein. The study provides evidence of a relationship between killer whale sighting probability and seasonal prey availability. Killer whales were present at the island year-round with a distinct seasonal peak in November–December, and coincident with a peak in occurrence of southern elephant seals (Mirounga leonina) due to breeding season activity, particularly the dispersal of weaned pups. Supporting this association and killer whales’ top-down influence on the survival of juvenile and adult southern elephant seals, pinnipeds accounted for 79% of prey identified, with weaned southern elephant seal pups contributing over a quarter of feeding events observed in the near-shore environment. Fur seals and penguins were also identified as prey. Killer whale groups had a median group size of three individuals, and groups of three to five individuals were most often observed feeding/milling in near-shore waters. The largest range in group sizes were observed during their peak occurrence in early summer, particularly in the number of sub-adult and female whales per group. Adult males made up 75% of single occurrences, and singletons were most often observed travelling. Overall, the ecology of killer whales at Macquarie Island was similar to that of killer whales studied at other Sub-Antarctic locations, with comparable seasonality, behaviour, diet, and group structure. Much remains to be learnt regarding the seasonal movements of whales and their diet at other times of year, their relationship to killer whales sighted in coastal Australian, New Zealand and Antarctic ecosystems, and impact on diet from commercial fisheries operations and fluctuating prey populations. en_ZA
dc.description.department Mammal Research Institute en_ZA
dc.description.department Zoology and Entomology en_ZA
dc.description.embargo 2019-11-01
dc.description.librarian hj2018 en_ZA
dc.description.uri en_ZA
dc.identifier.citation Travers, T., van den Hoff, J., Lea, MA. et al. Aspects of the ecology of killer whale (Orcinus orca Linn.) groups in the near-shore waters of Sub-Antarctic Macquarie Island. Polar Biology (2018) 41: 2249-2259. en_ZA
dc.identifier.issn 0722-4060 (print)
dc.identifier.issn 1432-2056 (online)
dc.identifier.other 10.1007/s00300-018-2361-y
dc.language.iso en en_ZA
dc.publisher Springer en_ZA
dc.rights © Springer-Verlag GmbH Germany, part of Springer Nature 2018. The original publication is available at : http://link.springer.comjournal/300. en_ZA
dc.subject Killer whales (Orcinus orca) en_ZA
dc.subject Diet en_ZA
dc.subject Feeding behaviour en_ZA
dc.subject Group size en_ZA
dc.subject Southern elephant seal (Mirounga leonina) en_ZA
dc.title Aspects of the ecology of killer whale (Orcinus orca Linn.) groups in the near-shore waters of Sub-Antarctic Macquarie Island en_ZA
dc.type Postprint Article en_ZA

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