Restoration goals and planning

Project beginnings

Te Urewera Mainland Island was established in 1996. Initial work focused on a region known as Otamatuna in the Waimana/Tauranga River catchment. Here, a remnant population of North Island kokako was being protected through control of the introduced brushtail possum.

Rat preying on blackbird nest

Surveys in the early 1990s had indicated that the forests of northern Te Urewera contained the world's largest population of kokako. However, the population was found to be in rapid decline. At Otamatuna, the 16 pairs found in 1991/92 had decreased to eight pairs in just two years. After possum control was initiated in 1993 the population had recovered to 12 pairs by 1996.

The project's vision is: To acknowledge and nurture the mauri of the northern Te Urewera ecosystem. The word 'mauri' can be translated as 'spirit' or 'life-force', and therefore the vision statement represents a holistic goal encompassing spiritual as well as environmental values.

The vision is a broad statement and is supported by more specific management objectives as listed in the initial 1996 strategic plan. This plan is currently under revision and it is expected that the updated version will more strongly reflect the eight guiding management principles for Mainland Islands, grouped under the three themes of Learning, Biodiversity and Community.

In Te Urewera, the greatest threat to native plants and animals comes from mammals introduced by humans either accidentally or purposefully. Before humans arrived in New Zealand, the only land mammals present were three species of native bat (one of these is now extinct).

Today, the forests of Te Urewera (and elsewhere) have to deal with:

• Brushtail possum (introduced from Australia as a source of fur)
• Ship rats (escapees from European ships)
• Stoats (introduced to control rabbits, but didn't!)
• Red deer (introduced as a game animal).

These animals and others like wild cats, dogs and pigs, eat or compete with the native plants and animals which unfortunately have barely any form of defence against these newcomers.

Having previously survived for millions of years, some species became extinct following the arrival of introduced mammals, and others became confined to predator-free offshore islands.

Some of the species that did persist in Te Urewera were continuing to decline in the face of ongoing predation. It was clear that if we did not reduce the numbers of introduced mammals in our forests and elsewhere, further species would also disappear forever.

Management approach

The project vision incorporates the entire northern Te Urewera landscape. This is a large area covering tens of thousands of hectares, and it is not currently possible to control introduced mammal numbers over this entire area. The approach used is to start with a smaller area and to develop management techniques that we know work. Then we can work out how to apply these techniques over the wider landscape.

The best way to develop good management techniques is to undertake the work in a structured way so that by doing one type of management we know we get a particular result. This is what DOC Mainland Islands are about; trying and testing management techniques so we can help the native plants and animals not only at these sites but at the many others around the country and overseas.

Possum kill trap

When Te Urewera Mainland Island started in 1996, the first study site chosen was Otamatuna. Here, possums, rats and stoats were being controlled to help the native plants and animals, especially (but not only) kokako.

In time this site was referred to as the Otamatuna Core Area to distinguish it from the surrounding area where only possum control (not rat or stoat control) was being done. The possum-only control area is now referred to as the Background Area.

Over the longer term, we envision having many Core Areas spread through the landscape of northern Te Urewera and even beyond. There is a lot of work to do before we know exactly how we are going to achieve this.

Instead of trying to control the introduced animals everywhere, we will have pockets of low pest numbers (the Core Areas) where the native birds and plants will survive and spread beyond these sites. Surrounding these Core Areas will be the Background Area where lower intensity pest control work will provide some ecological benefits.

Unlike many other similar projects in New Zealand which use toxins, within Te Urewera Mainland Island we mainly control animal pests by using traps. There are particular pros and cons for each approach. However, one of the most important aspects is that the use of traps is far more readily accepted by the local communities than the use of toxins on a wide scale.

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