<I>Rattus exulans</I>

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

Major trends in forest successions following fires are identified for northern offshore islands of New Zealand. Data are from the author’s observations over several decades, and published descriptions. Islands studied extend from the Cavalli group in the north to the Aldermen group in the south. Their original vegetation was largely destroyed by human-induced fires. Successions that followed were dominated for several centuries by pohutukawa (Metrosideros excelsa) or, for a shorter time, by kanuka (Kunzea ericoides).

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.

The kiore or Polynesian rat (Rattus exulans) has been suggested as the probable cause for reduced reptile, seabird and invertebrate faunas on many of the northern offshore islands of New Zealand, but the evidence is largely circumstantial and it is based on comparisons between islands with and without kiore. In 1977, kiore colonised a small island in the Mokohinau Group (Hauraki Gulf), where they caused a dramatic drop in lizard numbers. Their impact upon seabirds appeared minimal.

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.

We outline the scope of this special issue of New Zealand Journal of Ecology, which reviews progress in New Zealand ecology to 2009, based on a symposium in 2007. Both the issue and symposium update a 1986 conference and 1989 special issue of NZ J Ecol called “Moas, Mammals and Climate” which has been influential and widely cited.