At a cost of NZ$2.2 million a highly specialised pest-proof fence, just under 2 metres tall and 8.7 km long has been erected to enclose the site. The fence is designed to keep out all introduced mammals such as possums, rats, stoats, ferrets and cats. The stainless steel mesh is sufficiently fine to prevent baby mice from entering and continues down to form a skirt at ground level that prevents animals from burrowing underneath the fence.
On the top is a steel hood that prevents climbers like cats and possums from passing over the top of the fence and outside the fence a clearance of 4 metres prevents pests from using neighbouring trees to leap into the Ecosanctuary.
An electronic surveillance wire alerts Ecosanctuary staff when anything hits the fence or when the culvert screens or any other gates are left open. It is operational 24 hours a day. It is also closely inspected by volunteers on foot several times a week to check for damage that might allow pests through and compromise the safety of the Ecosanctuary and its wildlife. Special culverts and water gates allow native fish to swim in and out of the ecosanctuary while preventing access by pest animals, even when the stream is in flood.
The eradication programme has removed 12 species of pests and has been followed by an intensive monitoring programme across a grid of 64 kms of monitoring tracks through the entire ecosanctuary. This is improving the health of the forest ecosystem and providing safety for vulnerable native flora and fauna.
Restoration of the forest ecosystem entails weed removal, replanting with native species that are historically local to the area and the return of our lost birds, reptiles and bats. High on our current list of species to bring back home are kiwi, tuatara, and kakariki.