The effects of vegetation removal on rabbits (Oryctolagus cuniculus) and small mammalian predators in braided riverbeds of the Mackenzie Basin

Abstract

[Executive Summary] (…) Predation by cats, ferrets and stoats (Mustela erminea) has been identified as a major threat to several species of birds which nest in open riverbed areas of the Mackenzie Basin, South Canterbury, New Zealand (Pierce 1987). Lagomorphs, particularly rabbits are an important prey of these carnivorous predators and manipulations of rabbit numbers may therefore be an important tool in controlling predator abundance (King and Moors 1979, Alterio 1994). This study aimed to describe the diet of cats, ferrets and stoats in riverbeds and farmland of the Mackenzie Basin in order to determine the relative importance of individual prey species to predator diet. Project River Recovery (Department of Conservation, Twizel) hypothesised that removal of large areas of willow (Salix spp.) from the Tekapo Riverbed would enhance feeding and nesting habitat for riverbed birds, lower rabbit and predator abundance in the area and thereby decrease the amount of predation on birds and other endemic biota in the system. The relationship between vegetation and the relative abundance of lagomorphs and predators of riverbed nesting birds was examined in this study. (…)