New Zealand

This report estimates the benefits of making Rakiura and surrounding islands predator free. The proposal is to do this in two phases, starting with the Halfmoon Bay area (denoted in this report as HMB) before progressing to the rest of the island (denoted in this report as full).

Since 1987, I have assisted the Cook Islands Conservation/Environment Service and, more recently, the Takitumu Conservation Area Project and the Avifauna Conservation Programme of the South Pacific Regional Environment Programme (SPREP) to plan and implement a recovery programme for the kakerori, a critically endangered forest bird endemic to Rarotonga. In 1989, the kakerori was one of the 10 rarest birds in the world, and classified as 'critically endangered' (Collar et al. 1994) with a population of just 29 birds. I calculated

In winter 2016, the New Zealand Department of Conservation (DOC) eradicated mice (Mus musculus) from the Antipodes Islands located at 49°S 178°E, 760 km south-east of New Zealand’s South Island. Mice were the only mammalian pest species present. They have extensively impacted the abundance and survival of invertebrates, with likely secondary impacts on endemic terrestrial birds and nesting seabird fauna. Public-private partnerships with DOC instigated the project and provided essential financial support.

Eradication of introduced species from inhabited islands requires consideration of both technical and social feasibility. Historically, biologists have struggled to engage successfully in the social components of eradication planning. Island communities have unique features that require consideration in eradication planning. Social impact assessment is a powerful planning tool used widely outside of wildlife management. We outline the core components of a social impact assessment as it could be applied to eradication planning on inhabited islands.

Predators play a critical role in ecosystems; however, when overly abundant, they can disrupt natural processes and cause extinctions of species. In particular, oceanic islands have endured many impacts of introduced mammalian predators. Whereas knowledge and management of introduced mammalian predators on islands is well advanced in natural landscapes, in inhabited landscapes, spanning rural and urban environments, comparatively less is known.

The impacts of house mice (Mus musculus), one of four invasive rodent species in New Zealand, are only clearly revealed on islands and fenced sanctuaries without rats and other invasive predators which suppress mouse populations, influence their behaviour, and confound their impacts. When the sole invasive mammal on islands, mice can reach high densities and influence ecosystems in similar ways to rats.