Stewart Island rat, cat and possum eradication
- scoping and future plans

Brent Bevan explores recent community dialogue on Rakiura
whose predator problems parallel our own on Great Barrier Island


Stewart Island and Great Barrier Island have a connection derived from the common unique experience of living in small island communities.

In recent years, both communities have started discussing the concept of eradicating several pest animals from the islands. The discussions are often emotive and sometimes heated as the topic not only includes the technical practicalities of “if” and “how” this eradication could be achieved, but also the potential impacts (both positive and negative) on the island’s individuals, the community and the very fabric of what makes island living unique.

Peaks at Port Pegasus, southern Stewart Island (E.Ganley. 
From the Stewart Island Scoping Document, with permission).

In this article I attempt to explain how the Stewart Island community has dealt with this debate, what actions have been achieved and where we will go from here.
In 2006, the Tindall Foundation funded an investigation into the feasibility of eradicating rats, cats and possums from all of Stewart Island. This funding was held by the Stewart Island Community and Environment Trust (SIRCET), who contracted DOC to complete the work.

The feasibility study took a year to write, involving a review of current knowledge about eradications around the world, as well as discussions with the community about concerns and potential solutions. The report draws all of these together.

In general, it appears to be technically feasible to eradicate these pests from Stewart Island, but there are a number of risks and concerns that were identified that need to be managed or have solutions found. The benefits identified by the process were large. These included not only ecological benefits, but also financial and social benefits.

One of the overall principles of the process was that an eradication of this nature can’t be “owned” by any one individual or organisation. Those who are going to be affected by the operation need to have a strong say in the planning of the operation, thus a “steering group” needs to be formed if this project is to progress. The steering group will be made up of representatives of key stakeholders. This theme is further strengthened in the feasibility study through the suggested use of working groups to solve some of the issues. For example, a concern was voiced about the potential impact of an eradication operation on deer and deer hunting opportunities. There are a number of management solutions, but the best people to find the solution are those who know the issue best; deer stalkers need to be strongly involved in the working group to determine how to satisfactorily address this issue.

This principle has recently been published as a model for eradicating pests from inhabited islands around the world. Oppel et al1 found that involving the community in the planning of the project, right from the start, was an essential ingredient of success for eradication operations on inhabited islands.

So, in summary, the feasibility study concluded that: it appears to be technically feasible to eradicate rats, cats and possums from Stewart Island; there were some gaps in our knowledge that needed to be addressed; the community and others affected by the operation need to be actively involved in planning the operation.

Since the completion of the report in 2007, there has been a lot of thinking, but limited action. The recent draft Stewart Island Tourism Strategy has identified the eradication as a key driver to enhance the tourism product on the island. The strategy also tries to balance potential visitor growth with the protection of the community’s values. The DOC National Park Plan also had overwhelming support for the eradication principle during the public submission process. These are both positive steps that take us closer to the eradication of these three animal pests from Stewart Island.

Perhaps the key step that needs to occur now is the formation of a steering group to drive this idea forward. I am confident that this will happen and the whole island will eventually be cleared of these pests. It will happen in its own time and at a pace that suits the island. But, be it 5 or 50 years, it is an idea whose time has come.

1 Oppel et al (in press). Eradication of invasive mammals on islands inhabited by humans and domestic animals. Conservation Biology.