Loss of flight ability in the extinct New Zealand duck Euryanas finschi

Abstract

Subfossil bones of the extinct New Zealand duck, Euryanas finschi (Van Beneden), from late Otiran glacial‐early Holocene (20,000‐ 1 1,000 years BP) and late Holocene (2,000‐1,000 years BP) deposits were compared. Ten percent reduction in wing bone lengths and reductions in other pectoral girdle elements suggest reduced flight ability and may be related to possible ecological changes such as relaxation of predation pressure and increase in stability of food supply. Comparisons of Euryanas with extant members of the Anus aucklandica (Gray) species complex indicate that in the late Holocene Euryanas had similar flight ability to A. aucklandica chlorotis Gray, 1845.

Quaternary fossil faunas from caves in the Punakaiki area, West Coast, South Island, New Zealand

“…For these reasons, the specimen was referred to Finsch's duck. Because its restored length of about 90 mm is outside the range measured in Holocene populations but similar to bones of Otiran age (Worthy, 1988c), it is probably contemporaneous with the dated Otiran moa bones from the same site.…”

“…Most specimens were complete bones. The complete humerus from Babylon measured 90.5 mm long, outside the Holocene size range, but average for Otiran bones of this species (Worthy, 1988c). Similarly, the humerus from Cave 4 was over 90 mm long and so was probably of Otiran age.…”

Avifaunal changes revealed in Quaternary deposits near Waitomo Caves, North Island, New Zealand

“…The fauna is undated but the lengths of the carpometacarpi and femora of Euryanas finschi indicate these individuals had relatively long wings typical of specimens of Glacial age (Worthy 1988b(Worthy , 1997. The fauna is therefore probably of pre-Holocene age, but it has not been dated.…”

“…The lower level, or main Henry Lambert Passage, was then also abandoned by the stream. The age of the nearby rockfall (ZW4) is unknown, but the presence of Euryanas finschi with relatively long wings suggests a Pleistocene age (Worthy 1988b(Worthy , 1997.…”

Late Holocene extinction of Finsch's duck(Chenonetta finschi),an endemic, possibly flightless, New Zealand duck

“…Measurements of specimens of late Pleistocene (Otiran glaciation) and Holocene age dated by radiocarbon show that the wing in Finsch's duck declined in length over the past 25 000 years without an accompanying diminution in body size (Worthy 1988). While it is debatable whether the bird had become flightless, it is likely to have been facultatively so, and extremely reluctant to take wing (Worthy 1988). Hence, although almost all waterfowl become flightless and vulnerable during the post-breeding simultaneous moult of the primary feathers, Finsch's duck would have been vulnerable to human hunting throughout the year.…”