What limits kiore (.rattus exulans) distribution in new zealand?

Abstract

The kiore, once common throughout New Zealand, had disappeared from most of the country by the end of the 19th century, and is now found only on certain olfshore islands and in areas of Fiordland where at least one of the three introduced European rodent species is absent. It is usually accepted that the kiore was displaced by ship rats (Rattus r. rattus) and Norway rats (R. norvegicus). However, recent investigations on Stewart Island have revealed kiore, ship rats, and Norway rats living in close association, but in the absence of mice (Mus musculus). In the area studied the kiore seemed to inhabit mainly grassland. Re-examination of possible reasons for the decline of the kiore strongly suggests that competition from mice has been a major contributing factor. It seems that in New Zealand a niche no longer exists for kiore once mice, ship rats, and Norway rats have all become established. © 1975 Taylor & Francis Group, LLC.