Drainage is a recognised cause of wetland loss worldwide, and New Zealand is no exception. In the last 200 years drainage has reduced the natural extent of wetlands in New Zealand by c. 90%. Avoiding further loss is a national priority. Despite recent reform to restrict new drains within 100 m of existing wetlands in New Zealand, little is known about the extent and effect of existing drains in and near wetlands.
Conservation programmes in New Zealand often suppress populations of a single invasive predator for the benefit of threatened avifauna. However, the establishment of whole guilds of invasive species has created complex competitor and predator-prey relationships, including some well-described trophic cascades. Trap networks designed to target stoats (Mustela erminea) are poorly optimised to supress a population of weasels (M. nivalis), and may contribute to periodic spikes in weasel numbers due to decreased interspecific competition and aggression.
A resetting toxin device (the “Spitfire”) has been designed that delivers a toxic paste to a rat’s ventral surface when it passes through a tunnel. The rat grooms off the paste and ingests the toxin. The system was assessed in cage trials and one field trial. The purpose of the cage trials was to investigate whether a range of toxins can be delivered by the Spitfire to rats (Rattus rattus and R. norvegicus), namely 0.55% sodium fluoroacetate (1080), 0.2% brodifacoum, 15% cholecalciferol, and 12.5% zinc phosphide.
Fairy prions, Pachyptila turtur, breed in large numbers on Stephens Island in north-western Cook Strait. The 1974-75 breeding cycle was followed with the aid of observation burrows. Laying, hatching and chick departure times were between those previously observed by Harper (1976) on the Poor Knights Islands and Richdale (1945, 1965) in Foveaux Strait. Tuatara, Sphenodon punctatus, are also numerous on the island and often share burrows with the prions.
Information on diameter frequency distributions and spatial patterns, together with estimates of diameter growth and mortality, are used to draw up regeneration balance sheets for three stands of red beech (Nothofagus fusca) on Mount Colenso, New Zealand. Because large canopy gaps are a feature of these forests, attention is directed particularly to their future status. It is concluded that, in the short-term, a further opening of the canopy is likely in the higher altitude forest.