The predator-proof fence
Following recommendation from a feasibility study (Oecologico, 2005) the trust began the challenging task of fundraising for a $1.9M predator-proof fence to circle the 8.2km reserve perimeter. Due to overwhelming public and sponsor support, Xcluder Fence Company began construction work on this specially designed fence in November of 2006. It took just over 2 years to complete, but this included breaks over winter due to the steep and slippery nature of the surrounding terrain.
Not just any ordinary fence!
Unlike your standard stock or garden fence, this fence has special features which make it a barrier to unwanted predators:
a height of close to 2 metres stops jumping animals such as cats getting over;
a fine stainless steel mesh (25mm x 6mm) is small enough to stop even baby mice from getting through;
a smooth rolled hood helps to prevent animals such as possums from getting a grip to climb over; and
the fence has a skirt which goes underground to act as a barrier to digging animals such as rabbits and hares.
The Rotokare fence follows a ridgeline, therefore making it less likely to be damaged by falling trees. This also means that the entire head water catchment is enclosed within the fence, preventing any contaminants entering the reserve from surrounding land.
The fence also has a surveillance system. An electric wire runs around the top of the fence. Should a tree fall on the fence, the wire is shorted on the metal pigtails which it passes through, and a text message is sent to the Site Manager. This allows fast and efficient repairs to be made before any sneaky pests can get in.
Why do we need to fence areas of remaining forests in New Zealand?
Introduced pest animals are one of the greatest threats to New Zealand's unique wildlife and habitats. Such pests and predators are found throughout New Zealand and although good control methods (poisons and trapping) exist, the fence is currently the most sustainable method of controlling these pests to very low levels. Volunteer burn-out or long-term use of toxins is a risk Rotokare Trust wanted to avoid.
Such a fence allows opportunities for high-level restoration - with a barrier to invading animals, pests and predators inside can be completely eradicated - making it safe to reintroduce many of our vulnerable native animals.