<I>Rattus norvegicus</I>

He nui nga mātauranga a te Māori (Ngai Tūhoe) e pā ana ki nga momo hua tāokeoke (Toxins) e taea ana te whakarite hei rauemi tāwai i ngā riha kīrearea, pērā anō ki nga whiu takarangi o te tāoke 1080. I whakamātauhia e matou i nga ira tāoke o roto o te hua Tutu, ki rō taiwhanga pūtaiao. Mā te wero atu ki tētahi kiore (Norway Rat) i hua mai ngā mohiotanga o te nui me te momo o ngā tāokeoke kei roto i tēnei miro Māori, me te āhua o tēnei tāoke kia mau-rohā tonu tōna tuku whakahemo (Humaneness).

Ecological research into rodents in New Zealand commenced in the late 1940s with the creation of the Animal Ecology Section, Department of Scientific and Industrial Research (DSIR). Field surveys of rodents were backed by study skins and skeletal material. Supplemented by specimens from the Wildlife Service and the public, these accrued over the next 45 years laying the foundation for our present knowledge of rodent distribution. In 1951, J. S. Watson joined the DSIR from the Bureau of Animal Population, Oxford, and brought much needed experience in rodent biology and control.

Norway rats (Rattus norvegicus) were present on Whale Island (Moutohora), Bay of Plenty, New Zealand between about 1920 and 1987. During 1969-1971 they reduced by less than 10-35 % the breeding success of grey-faced petrels (Pterodroma macroptera gouldi), by eating unattended eggs and killing young or weak chicks. Rabbits (Oryctolagus cuniculus), introduced to Moutohora (240 ha surface area) in about 1968, multiplied rapidly to reach a density of up to 375 individuals/ha by early 1973.

Eradication of rodent species from some offshore islands has proved to be an effective means of conserving native animal communities and restoring natural ecological processes on the islands. As methods of eradication differ fur different rodent species, a truthful monitoring method to detect species presence and relative density is essential for a successful eradication programme.

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.

Norway rats were eradicated on bush-covered Hawea Island (9 ha) in Breaksea Sound, using the anticoagulant rodenticide "Talon 50 WB" (brodifacoum). The work was done as a conservation measure and to evaluate the feasibility and costs of eradicating rodents quickly from islands. The 50-100 rats present were eradicated in about two weeks by applying a simple strategy that took full account of the characteristics of the poison, he environment, and the behaviour of the target species.

The Noises and Motukawao Islands in Hauraki Gulf are small (maximum size 26 ha) and bush— clad, and none is permanently inhabited. Norway rats reached the Noises about 1956, but their history on the Motukawao group is unknown. Live and kill-trapping was carried out between August 1977 and December 1981, mainly on the Noises Islands. Trapping success was high initially but declined rapidly and remained very low after mid-1978. Rats travelled widely between consecutive captures in live-traps and three home ranges of males averaged 1.2 ha.

The Norway rat (Rattus norvegicus) is a highly destructive invasive species but while rat eradications on islands are effective, detection of survivors or reinvasions is challenging. We tested whether laboratory rats can act as lures for wild rats. We live-trapped rats first by using food baits, followed by live trapping using male and female lure rats vs controls (i.e. the same trapping device but without the lure animal). Norway rats were more frequently attracted to lure rats compared with controls. There was no sex bias in the trapped animals.

Multiple paternity within litters has been recorded among a variety of small mammal species, including some species of rodents. Although multiple mating has been observed in wild Rattus populations, whether such mating results in litters with multiple paternities has not been established previously. For studies involving invasive species, awareness is useful of the level of genetic diversity a single pregnant invader can bring to a population.

Norway rats (Rattus norvegicus) were eradicated from Ulva Island, Rakiura National Park, in 1996. The aim of our work was to determine if seedlings and saplings increased in density and/or species richness following this eradication. In 2003, we took advantage of eight permanent plots (5 × 5 m) that had been established on Ulva Island in 1991, by counting seedlings and saplings of woody species, including tree ferns. Over this period, total numbers of woody seedlings (< 30 cm tall), and saplings (30 cm – 2 m tall) did not increase significantly (P > 0.05).