avifauna

New Zealand flowers are frequently considered unspecialised allowing easy access to pollen and nectar by a wide range of visitors. Most conform with a syndrome of insect pollination (entomophily). Pollination of forest flowers by birds has been described for a range of species whose flowers are morphologically ornithophilous. On Kapiti Island and Little Barrier Island, all three species of New Zealand honeyeaters have been described feeding on flowers currently assumed to be entomophilous or where the pollination system is unknown.

This paper reviews current knowledge of dynamic processes in New Zealand land-water ecotones drawing on published quantitative data wherever possible. Basic ecosystem processes in forested and natural unforested land-water ecotones are compared, and dynamic processes are discussed under the following headings: time scales of change; water movement; sediment trapping and transport; dissolved nutrient dynamics; dissolved oxygen; trophic interactions.

In the past 1000 years New Zealand has experienced a major 'extinction event', losing 40-50% of the avifauna, at least 50% of the frog fauna, and unknown proportions of the lizard and invertebrate faunas. During this period, bird species became extinct at different times and rates depending on the particular aspects of their ecology and life history which made them vulnerable to habitat loss, hunting, predation, and competition for food resources. Three groups of species with different levels of vulnerability are recognised within this event:

The takahe (Notornis mantelli), an endangered rail once widely distributed through New Zealand, had become restricted to Fiordland, and possibly Nelson and the Ruahine Ranges, by European times. Two contentious viewpoints have been advanced to explain the decline: climate and vegetational changes in the late Pleistocene and Holocene; and ecological changes induced by early Polynesians. These theories are examined in relation to the habitat requirements of takahe in its present restricted range, the historical and sub-fossil record, and the possible age of the sub-fossils.

This paper considers how habitat geometry affects New Zealand bird distributions on land-bridge islands, oceanic islands, and forest patches. The data base consists of distributions of 60 native land and freshwater bird species on 31 islands. A theoretical section examines how species incidences should vary with factors such as population density, island area, and dispersal ability, in two cases: immigration possible or impossible. New Zealand bird species are divided into water-crossers and non-crossers on the basis of six types of evidence.