Two species of rat (kiore or Pacific rat Rattus exulans and Norway rat R. norvegicus) coexisted on Kapiti Island (1965 ha) until 1996, when they were simultaneously eradicated. I radio-tracked rats of both species from June 1996 to September 1996, when the first of two aerial poison drops occurred. The aim of the study was to describe the home-range parameters of both species of rat in an area of grassland where they coexisted. Radio-tagged kiore occupied overlapping home ranges that varied from 26 to 89 m in diameter.
On three island groups off the northeast coast of New Zealand, fewer lizard species and markedly fewer individuals occurred on islands inhabited by Polynesian rats or kiore than on other islands without rats. Nocturnal, ground-dwelling lizards that forage in the open were most affected, which suggests that predation by kiore is the cause. The generally low densities and disjunct distributions of some lizards on the New Zealand mainland may have resulted from the introduction of kiore at least 600 years ago
The results of a survey of the presence and populations of the tuatara (Sphenodon punctatus) and the Polynesian rat or kiore (Rattus exulans) on 35- islands off the New Zealand coast are presented and discussed. Tuataras were found on 23 of these, and on six they occur with kiore. The age distributions and densities of the tuatara populations suggest that decline because of failure of recruitment is occurring on seven—the six kiore -inhabited islands and one other.
Pollen and charcoal analyses of sediments from northern coastal Taranaki, New Zealand, show that Maori settlement impacts on the vegetation began with the burning of tall coastal forest in the mid-17th century. Forest was replaced with a fern-shrubland, and small wetlands expanded with changing hydrological conditions. This forest clearance was much later than in most regions of the country, where major forest disturbance and clearance began between AD 1200 and AD 1400.
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.
Kiore (Rattus exulans) carry food to husking stations to feed, where they are sheltered from predators, competitors and rain. On four northern offshore islands of New Zealand remains of plant foods left in husking stations and in the open included seeds, leaf laminae, shoots, bark, flowers and root bases. A wide variety of animal remains were identified in husking station material, from habitats as diverse as tree tops and below the ground. All stages of both small social and large solitary insects were eaten.