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

Abstract

Finsch's duck (Chenonetta finschi), an extinct, possibly flightless New Zealand endemic, was widely distributed and apparently abundant immediately before human settlement of New Zealand, but its bones have rarely been identified in archaeological sites. Its extinction has been variously attributed to habitat changes, predation by the introduced Pacific rat (Rattus exulans), and human predation. Discriminating between possible causes of its extinction hinges on determining the relative timing of phases of the extinction process and the arrival of rats and humans. Methodological problems of determining the time of extinction of fossil species are reviewed. Bayesian statistical analysis of a series of accelerator mass spectrometry 14 C ages on gelatin from Finsch's duck bones from non-cultural deposits suggests that the species began to decline before widespread Polynesian settlement and that it was much reduced in range and numbers by the time extensive human predation and habitat alteration began. Possible causes of its extinction after Polynesian settlement are discussed.

Bone stable isotopes indicate a high trophic position for New Zealand’s extinct South Island adzebill (Aptornis defossor) (Gruiformes: Aptornithidae)

“…use of open vs. sub-canopy habitats) are the two most likely factors differentiating the δ 13 C values of these species at Finsch's folly tomo. Holdaway et al (2002) and Worthy and Holdaway (2002) also reported relatively depleted 13 C values for Finsch's duck, the latter authors suggesting this result reflected feeding beneath a dense canopy. However, it can be difficult to attribute any one factor to explaining δ 13 C values (Dawson et al 2002).…”

Late Holocene extinction of the New Zealand owlet‐nightjarAegotheles novaezealandiae

“…If a site contained the remains of taxa introduced by Europeans and the remains of extinct taxa, it was assumed that the record in that site was continuous through the period of interest. Holdaway et al (2002). AMS 14 C dates are reported as conventional radiocarbon ages (CRA, years BP) as defined by Stuiver & Polach (1977), and as calibrated dates.…”

“…Using 12 of the 20 determinations on A. novaezealandiae bone, we sought to establish the time range over which the extinction of this species occurred using the Bayesian model presented by Holdaway et al (2002) to examine the extinction of Finsch's duck (Chenonetta finschi). Briefly, assuming that the dated capture events (an owlet-nightjar caught by a laughing owl) can be described as a constant rate Poisson process (this describes discrete random temporal events of relatively low temporal frequency), we can compute posterior distributions for parameters of interest via sample-based Bayesian inference.…”

“…Calibrated dates were used for the reasons given by Taylor et al (1996). N in bone gelatin samples were measured at the Rafter Laboratory using the method described in Holdaway et al (2002).…”

Establishment and extinction of a population of South Georgian diving petrel(Pelecanoides georgicus)at Mason Bay, Stewart Island, New Zealand, during the late Holocene

“…These distributions can then be compared with others for the establishment of predators or other potential factors in the extinction. Such probability distributions are available at present for only two species, Finsch's duck (Holdaway et al 2002a) and the New Zealand owlet-nightjar (Holdaway et al 2002b). Those analyses suggest that both species may have started their declines towards extinction before the most recent estimates for initial Polynesian settlement of AD 1280-1300 (Higham et al 1999;Lowe et al 2000).…”