eradication

Antipodes Island is part of New Zealand’s World Heritage subantarctic region and hosts special biodiversity values and significant species endemism. Invasive house mice were the only introduced mammal and detrimentally impacted invertebrate and native bird communities. Eradication of mice from Antipodes Island was undertaken in 2016 and confirmed in 2018. We present the monitoring used to confirm eradication of mice and the ecological outcomes measured over the 6 years since the eradication.

Auckland Island, the fifth largest island in New Zealand, is the only island in New Zealand’s subantarctic region where introduced mammalian pests remain (pigs, Sus scrofa; mice, Mus musculus; cats, Felis catus). The island has unique biodiversity and is a key site for progressing New Zealand’s goal to be free of several introduced predators by 2050. Recent island eradication successes have rekindled interest in eradicating pests from Auckland Island, and for the first time considering all three pests in one project.

The house mouse (Mus musculus) is considered the most difficult rodent species to eradicate from islands. Eradication projects require careful planning and execution of an ‘over-engineering’ approach to ensure every individual of the targeted population is encountered and removed. Aerial broadcasting of rodenticides has been the method of choice for island rodent eradications since the 1990s and the methods and parameters continue to be refined.

House mice (Mus musculus) are an invasive species on Auckland Island in the New Zealand subantarctic and planning for their eradication is underway. Mast seeding events cause rodent populations to irrupt, though little is known about this phenomenon in snow tussock grass (Chionochloa spp.) systems on Southern Ocean islands. The aim of this study was to understand population fluctuations of mouse abundance on Auckland Island for the 2 years following a mast event, and with which tools to monitor abundance, to inform planning of bait application for eradication.

As a major threat to New Zealand’s biodiversity, feral cats (Felis catus) are the subject of planned eradications on a number of offshore islands, including Rakiura Stewart Island. We used camera traps to estimate population density of feral cats on the north-east coast of Rakiura, and to investigate their movement behaviour and detection probability. We also used camera footage to compare the consumption of two types of non-toxic sausage baits (chicken and rabbit) with a view to future use of toxic baits.

Primary poisoning is an important method to ensure the successful eradication of cats (Felis catus) from large islands. Poison bait options for feral cat eradications and landscape-scale control in New Zealand are limited at present. As part of the development of a toxic bait for cats that can be aerially distributed, a nontoxic palatability trial was undertaken on Auckland Island to compare three types of prototype meat-based bait and one currently registered fishmeal polymer pellet for their palatability to feral cats and non-target species.

In order to conserve important biodiversity values, eradication of feral cats (Felis catus) is planned on Auckland Island in the New Zealand subantarctic region. This eradication will require detailed knowledge of the abundance, distribution, movement behaviour and detection probability of cats on the island. We investigated these parameters on a peninsula at the northern end of the island using live trapping, camera trapping, and scat searches with and without detection dogs. Here, we compare the results of these methods, and discuss their utility for the planned eradication.

Restoration initiatives of ecosystems transformed by human actions require optimisation of eradication measures of introduced species, particularly in fragile insular ecosystems. We studied aspects of the spatial ecology of introduced feral cats (Felis catus) on subantarctic Auckland Island of New Zealand to assist eradication efforts of pests from this remote, biologically rich island. Firstly, we estimated home range sizes and identified core areas of activity based on movement-rooted dynamic Brownian bridge models.

A feasibility study for removing feral pigs (Sus scrofa) from Auckland Island trialled feeders monitored by trail cameras to determine their effectiveness for detecting and attracting feral pigs. Ten automatic feeders were installed during January–February 2019 (summer) and again in August–September 2019 (winter) on Auckland Island. They delivered kibbled maize daily for a period ranging from 25 to 37 days. Sites selected for feeder installation needed to be of appropriate relief and area to allow feeder and trap installation, as would occur during an eradication operation.

Since their liberation in 1807, feral pigs (Sus scrofa) have negatively impacted ecosystem health and processes on subantarctic Auckland Island, New Zealand. Eradication of invasive alien species is often critical to restoration programmes and preventing species extinctions. Eradication programmes utilising multiple techniques have allowed feral pig eradications on large islands. Protracted eradication programmes can have a higher risk of failure due to factors such as biological, logistical, social, and funding support.