Mammalian Pests in the Waikato Region

Abstract

This project aimed to use camera traps to study the distribution of seven important mammalian pests across the three main vegetation types of the Waikato Region and to see if this method is a more informative alternative to other passive detection methods. For this study, the species of interest are the common brushtail possum (Trichosurus vulpecula), the European hedgehog (Erinaceus europaeus), ship rat (Rattus rattus), house mouse (Mus musculus), stoat (Mustela erminea), ferret (Mustela putorius), and weasel (Mustela nivalis).

The objectives of this study were to 1) calculate the distribution of each mammalian pest within the three main vegetation types of the Waikato Region 2) to determine site occupancy i.e. patchiness of species distribution within these habitats, and the probability of detection where they are present and 3) to evaluate whether the above parameters are influenced by the seasons and/or interactions between the species.

To meet these objectives, I measured five parameters related to site occupancy and activity levels for each species, and use the results to present an estimate of the proportion of the Waikato Region occupied by each species.

These analyses suggest that suggest that species distributions are very much dependent on habitat, but a large portion of all species was accounted for by pastoral areas. Even when species are not particularly abundant on pasture, it makes up more than half of the Waikato, and as such is potentially a source for reinvasions of controlled areas when not cleared in concert with the surrounding areas.