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Minimal similarity in songs suggests limited exchange between humpback whales (Megaptera novaeangliae) in the southern Indian Ocean

Authors

  • Anita Murray,

    1. Wildlife Conservation Society, Ocean Giants Program, 2300 Southern Boulevard, Bronx, New York, U.S.A. and Ecology, Evolution, and Environmental Biology, Columbia University, 10th Floor Schermerhorn Ext, 1200 Amsterdam Avenue, New York, U.S.A. E-mail: anita.murray1@uqconnect.edu.au
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  • Salvatore Cerchio,

    1. Wildlife Conservation Society, Ocean Giants Program, 2300 Southern Boulevard, Bronx, New York, U.S.A.
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  • Robert McCauley,

    1. Centre for Marine Science and Technology, Curtin University, P. O. Box U 1987, Perth, Western Australia, Australia
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  • Curt S. Jenner,

    1. Centre for Whale Research, P. O. Box 1622, Fremantle, Western Australia, Australia
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  • Yvette Razafindrakoto,

    1. Wildlife Conservation Society Madagascar Country Program, B.P. 8500, Antananarivo, Madagascar
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  • Douglas Coughran,

    1. Senior Wildlife Office, Marine Wildlife Operations, Department of Environmental and Conservation, Nature Protection Branch, Perth, Western Australia, Australia
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  • Shannon McKay,

    1. Deakin University Whale Ecology Group, School of Life and Environmental Science, P. O. Box 423, Warrnambool, Victoria 3280, Australia
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  • Howard Rosenbaum

    1. Wildlife Conservation Society, Ocean Giants Program, 2300 Southern Boulevard, Bronx, New York, U.S.A. and Ecology, Evolution, and Environmental Biology, Columbia University, 10th Floor Schermerhorn Ext., 1200 Amsterdam Avenue, New York, U.S.A.
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Abstract

Comparing humpback whale song from different breeding assemblages can reveal similarities in song due to acoustically interacting males, and therefore indirectly test whether males from different breeding sites are mixing. Northern Hemisphere song comparisons illustrated that whales within ocean basins share similar songs and are subpopulations within a larger population, whereas whales in different ocean basins are isolated populations and therefore do not share songs. During the 2006 breeding season, recordings were collected in Madagascar and Western Australia, and were compared visually plus aurally. Both regions shared one theme, whereas each region had four and six private themes, respectively. This study had a substantially low number of shared themes. The co-occurrence of one theme was interpreted as an indication of limited exchange between these breeding assemblages, and we speculate that limited song similarity is due to inter-oceanic interactions. Male(s) from an Indian Ocean breeding group could be exposed to novel song when they geographically overlap, and acoustically interact, with males from a different ocean basin. Novel song could induce rapid temporal changes as new song content is incorporated, thereby minimizing song similarities between that breeding group and other Indian Ocean breeding groups that were not exposed to the novel song.

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