The demography of kiore, Rattus exulans in three habitats

Abstract

A 17-month study on Rattus exulans, known in New Zealand as kiore, was carried out on Tiritiri Matangi Island 10 years after its ecology in forest and grassland habitats on the same island was first described (Published in Moller & Craig 1987). In this study three different habitats were included to determine the influence of environmental factors on the population dynamics of this species.

Populations underwent similar annual cycles in all three habitats. There were apparent differences between habitats in adult longevity, mean weights of immatures, time of onset of sexual maturity, and annual production of young. Results are compared with the predictions of Craig (1986) and Moller & Craig (1987); both models are found to be inadequate in certain respects. This study indicates that shelter may be an important influence, at least in temperate latitudes, and a likely confounding variable in models of kiore population dynamics.

A decline in annual production, including mean litter size, appears to have occurred since the earlier study. The likely influence of habitat changes on kiore demography, and hence the influence of kiore on other fauna, is briefly discussed.

Keywords:

• Rattus exulans
• kiore
• population demography
• reproduction
• litter size
• longevity
• habitat
• food
• shelter