Benthic invertebrates and samples of blue duck faeces were collected in September 1988 from sites along Manganuiateao River, central North Island, and in November 1988 from seven rivers and streams on the East Cape. The occurrence of invertebrate taxa in the faeces varied within and between rivers, and within pairs of birds and family groups on the East Cape. In both regions, most blue duck had been consuming large proportions of cased caddisfly larvae.
Feral cats became established on Raoul Island some time between 1836 and 1872; the prey available to them included a great variety of nesting seabirds, few of which are present now, landbirds and kiore (Rattus exulans). Norway rats reached the island in 1921, providing additional prey for cats, but also another potential predator of seabirds. The diet of cats is described from guts and scats collected between 1972 and 1980. Rats are the main food, with land birds second in importance, and seabirds are now a minor item.
In honeydew beech forest in the South Island of New Zealand, introduced Vespula vulgaris wasps are now very abundant. Approximated biomass estimates indicate that Vespula (mostly V. vulgaris) biomass (mean estimate at peak = 3761 g ha-1, averaged over the year = 1097 g ha-1) is as great as, or greater than combined biomasses of birds (best estimate = 206 g ha-1), rodents (up to 914 g ha-1 in some years, but usually much lower) and stoats (up to 30 g ha-1). Relative V.
Polynesian settlement of New Zealand (c. 1000 yr B.P.) led directly to the extinction or reduction of much of the vertebrate fauna, destruction of half of the lowland and montane forests, and widespread soil erosion. The climate and natural vegetation changed over the same time but had negligible effects on the fauna compared with the impact of settlement. The most severe modification occurred between 750 and 500 years ago, when a rapidly increasing human population, over-exploited animal populations and used fire to clear the land.
Withdrawal of the use of cheap, persistent organochlorine insecticides in New Zealand pastures has shifted the emphasis of insect pest control to non-chemical methods during the last 10-15 years.
Two conservation tools have been developed over the last 10–15 years for species on the New Zealand mainland that are vulnerable to introduced mammalian predators: landscape-scale predator trapping networks, and eradication of predators within mammal-proof exclosures. We tested whether these tools would allow population growth of critically endangered grand skinks (Oligosoma grande) and Otago skinks (O. otagense) over three years.
Opportunities now exist to establish pest-free areas on the mainland of New Zealand by eradicating introduced mammals from within predator-proof-fenced areas. This has increased opportunities to investigate how the native insect fauna responds to the eradication of introduced mammals. We examined the response of weta populations to mammal eradication in a before-after-control-impact (BACI) experiment within the southern exclosure on Maungatautari.
Reintroduction programmes need to be monitored as a way of gauging potential causes of their success or failure. This, in turn, can be used to improve the likelihood of future translocation success. Since the 1990s, stitchbird (or hihi: Notiomystis cincta) translocations have been intensively monitored, with comparisons between two of these projects (Tiritiri Matangi Island – a successful introduction, and Mokoia Island – an unsuccessful introduction) often compared and contrasted as a means of identifying factors important in translocation success for this species.
Compared with the effect of invaders on the native terrestrial fauna of New Zealand, interactions between native fishes and introduced trout (sports fish in the genera Salmo, Oncorhynchus and Salvelinus) are less well known and there have been fewer efforts to remedy their effects. Trout have caused widespread reductions in the distribution and abundance of native galaxiid fishes, a family dominated by threatened species.
The stomach contents of 158 hedgehogs captured at Macraes Flat, Otago, New Zealand, over two summers in 2000 and 2001 were examined for the occurrence of lizards. The remains of at least 43 skinks (both Oligosoma nigriplantare polychroma and O. maccanni) and one gecko (Hoplodactylus sp.) were found. Twenty-one percent (n = 33; 8 males and 25 females) of the examined hedgehogs had fed on skinks. Female hedgehogs ate significantly more skinks than did males.