Plant species preferences of birds were determined by comparing the proportional bird use of plant species during direct observations with the proportions of plant species present on point-height intercepts in lowland rimu (Dacrydium cupressinum) forest in North Okarito, Westland. Plant species and bird use of plant species were divided into 5 m height classes, and rimu trees were divided into four age classes (sapling, pole, mature, and old).
The abundance of birds in three different-aged stands (young, mature, and old) was examined at North Okarito, a lowland rimu (Dacrydium cupressinum) forest in Westland, using 5-minute counts, transect counts, and mist-netting. Most of New Zealand's common forest bird species were present in the study area, with relatively high numbers of brown creeper (Mohoua novaeseelandiae) and New Zealand robin (Petroica australis), and low numbers of kaka (Nestor meridionalis) and yellow- crowned parakeet (Cyanoramphus auriceps).
Stem density, basal area, vegetation cover and vegetation surface area were compared as measures of the proportions of plant species present in North Okarito Forest, South Westland, for use in determining bird preferences for plant species. In general, stem density estimates of the proportions of canopy species were about 10 times lower than basal area estimates. The converse was true for estimates of the proportions of sub- canopy and understorey species.
The diet of 871 stoats (Mustela erminea) caught within the Okarito Kiwi Sanctuary, South Westland, New Zealand, between 2001 and 2004 was studied by assessment of gut contents. Stoat and ship rat (Rattus rattus) captures were used as a measure of relative abundance over time, and rat and mouse (Mus musculus) abundance was indexed using tracking tunnels between spring 2002 and winter 2004. There were major increases in rat captures in spring of 2002 and again in spring of 2003. Stoat captures peaked in the following summers, as rat captures declined.