Feeding environments of New Zealand

Abstract

The likely feeding environments of individuals from each of the three populations of New Zealand’s extinct merganser Mergus australis were interpreted from stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N) in fossil bones and tissue from preserved skins. Analyses of feather and claws from 10 specimens from Auckland Islands indicated the birds fed predominantly on marine prey but that some freshwater-sourced foods may also have been consumed. Stable isotope values from three bones of mergansers from Chatham Island strongly suggest a marine feeding habit while those from two mainland New Zealand bones indicated the birds fed mostly in fresh water. Merganser bones found at a New Zealand lake (Poukawa) suggest this species occupied mainland New Zealand’s fresh waters at the time of first human settlement.