Northern giant petrel (Macronectes halli) populations are thought to be increasing at some locations around the world, decreasing at others. The size and status of their breeding populations within the New Zealand region, in particular, is poorly understood: reliable population estimates have never been made at 3 of the 5 breeding locations. A survey of pre-fledging northern giant petrel chicks on Antipodes Island, New Zealand during Jan 2000 yielded a count of 130. The total population was estimated to be c. 230 breeding pairs. Because of an absence of accurate historical surveys, the status of the Antipodes Is population is unknown.
The South Island takahe (Porphyrio hochstetteri), an endangered flightless rail, has been released on 4 predator-free islands to reduce the risk of its extinction. To determine the ability of these islands to support takahe populations, we studied takahe home range size and carrying capacity on one of the islands. We plotted the location of 4 takahe family groups (13 individuals) from Nov 1994 to Oct 1995 on Tiritiri Matangi Island. Mean home range size (95% Minimum Convex Polygon) was 20.7 ha, and tended to be smaller when the proportion of suitable habitat within each home range was higher. We estimate that Tiritiri Matangi can support up to 8 breeding pairs, based on the availability of suitable habitat and estimated individual habitat requirements. However, this number is likely to change in the future depending on the influence of population density increases and successional habitat changes on takahe spatial requirements.
The relationships, adaptations, and habits of the extinct, endemic Finsch’s duck (Anas finschi Van Beneden, 1875) from New Zealand were determined from skeletal comparisons. Finsch’s duck, usually placed in the monotypic genus Euryanas Oliver (1930), was found to be most similar to the Australian wood duck (Chenonetta jubata). Because the differences are mainly those associated with loss of flight, Euryanas is synonymised with Chenonetta, and the species should now be known as Chenonetta finschi.