The Fence

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There are two ways to allow indigenous fauna to recover. One is the continuous control of pests through the use of traps, toxins and hunting, as practiced at sites like the Rotoiti Nature Recovery Project. The second is the construction of a pest-proof fence and eradication of pests inside it. This is the option selected for the Brook Waimarama Sanctuary for several reasons:

  • continuous control of some pests (like rats and mice) is very difficult
  • some pests (like stoats and feral cats) can do considerable damage even when in very low numbers
  • some pests may boom in numbers some years (like rats and mice in response to beech seed) and can be almost impossible to control
  • it allows ‘zero’ pests to be achieved, resulting in a more rapid process of restoration and the introduction of the full range of species once present at the site, including the most endangered
  • it reduces the need to continuously apply poisons and the killing of pest animals is largely restricted to the initial eradication.

HOW DOES THE PEST-PROOF FENCE WORK?

Pest-proof fencing in New Zealand was developed independently by two groups, at Karori in Wellington and Cambridge in the Waikato, with each researching the climbing, jumping and digging abilities of different pests. Their designs were similar: a fine mesh too small for even baby mice to squeeze through, dug into the ground to prevent burrowing, as high as a deer fence to stop animals jumping in, with a curved metal cap to stop animals climbing over the top. Pest-proof fences have been in use in New Zealand since 1999. From a wetland at Omaha in Northland to a kiwi fence in a private forest in Stewart Island, they are providing protection for native species from mice, rats, weasels, stoats, ferrets, hedgehogs, rabbits, hares, possums, feral cats, dogs, goats, sheep, cattle, pigs and deer. While Karori Sanctuary was the first, the most ambitious is at Mt Maungatautari, near Cambridge, where a 37km fence stretches around a dormant volcano, enclosing over 3000 hectares of mixed podocarp forest.

FENCE RESOURCE CONSENT GRANTED

We have been granted resource consent for the 14km predator-proof fence that will create a 700ha native wildlife experience close to Nelson’s city centre. The independent commissioner appointed by the Nelson City Council announced the decision in late 2009, after hearings held in August. The period for any appeals to be lodged with the Environment Court has now passed without appeal, making the consents effective. The consents cover the pest proof fence and an associated network of walking and operational 4WD quad bike tracks. The groundwork for the consents had been a prime focus for the trust over the last two years, with a lot of input from trustees and specialist advisors. Trust patron Philip Woollaston said the consent was great news for the sanctuary project. “The optimism the consent gives us makes it a great time to be seeking the support we need to see the fence become a reality,” he said. “Planning the next phase of fundraising and sponsorship is already underway and having consent is reassuring for donors and the many members and volunteers who support the trust.” Conditions of the consent include weaving the fence line to avoid significant trees and to enclose stands of rare hinau and mountain totara, weed clearance and ongoing weed control, and comprehensive revegetation including salvage and propagation of plant material from along the fence route. All work is to be supervised by a qualified ecologist. Other conditions relate to minimising visual effects and provision of additional bus and car parking.

The commissioner, Camilla Owen, commented on the ‘manifest and significant’ benefits of the project. She said while there will be some disruption while the fence is constructed, ‘in the end a resource will be created which will be an enhancement of what is already present – the environment will be enhanced and preserved’. A copy of the Resource Consent decision is available for download here Resource Consent Decision
Karori Fence

Karori Sanctuary fence, the first large scale pest proof fence, was completed in August 1999. It is formed on the inside of a 3 metre wide track and is 8.6 kilometres long, completely enclosing the upper valley.