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Formidable carpal weaponry of Anas chathamica, Chatham Island’s extinct flightless duck

  • Publication Type

    Journal Article

  • Publication Year

    2015

  • Author(s)

    M. Williams

  • Journal Name

    Notornis

  • Volume, Issue

    62, 3

  • Pagination

    113-120

  • Article Type

    Paper

Keywords

Anas chathamica; carpal knobs; Chatham Island duck; intraspecific combat


Formidable carpal weaponry of Anas chathamica, Chatham Island’s extinct flightless duck

Notornis, 62 (3), 113-120

M. Williams (2015)

Article Type: Paper

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The Chatham Island duck (Anseriformes: Anatidae: Anas chathamica) had a pronounced and rugose enlargement to the tip of the processus extensorius at the proximal end of its carpometacarpus. This “carpal knob” was the equal in size of those found in some much larger waterfowl (e.g., steamer ducks, Tachyeres sp.), and was disproportionately larger than those of all other New Zealand waterfowl. The knobs on 20 carpometacarpi examined all showed evidence of continuous bone deposition at their tips and their use as weapons is implied. Comparisons with other duck species having similarly prominent and rugose carpal knobs suggests the Chatham Island duck maintained long-term pair bonds and occupied combined feeding and breeding territories year-round which both sexes defended belligerently.