A 500-year plan
Just minutes from central Wellington, a 225-hectare valley is the site of a radical conservation experiment. Zealandia Ecosanctuary has a 500-year vision: to restore a forest ecosystem to its pre-human state. The project began with the understanding that native New Zealand flora and fauna, having evolved for millions of years without land mammals, were defenseless against introduced predators. The solution was a world-first predator-exclusion fence.
Completed in 1999, the specialized fence runs for 8.6 kilometers, completely enclosing the valley. Its design resulted from extensive trials with nearly 200 animals to test their physical limits. The final structure is 2.2 meters high and incorporates three main features. A curved top-hat section prevents climbing by animals like possums and cats. A fine wire mesh, with gaps of just 6x50 millimeters, stops even very small mammals. Below ground, a woven mesh skirt extends 400 millimeters outwards to block burrowing animals. After the fence was sealed, an intensive nine-month program eradicated the 19 invasive mammal species trapped inside, from deer and possums to stoats and rats.
Life finds a way
With the predators gone, the sanctuary became a secure "ecological island" for reintroductions. Over 20 native species have been brought back, some absent from the mainland for more than a century. The most famous resident is the tuatara (Sphenodon punctatus), the only surviving member of the reptile order Rhynchocephalia, which flourished around 220 million years ago. The first 70 tuatara were released in 2005. By 2008, a nest was discovered, marking the first time in over 200 years that tuatara had successfully bred in the wild on New Zealand's North Island.
Other species now thrive within the fence. Little spotted kiwi (Apteryx owenii), once extinct on the mainland, were first released here in 2000. The sanctuary is a refuge for the flightless takahē (Porphyrio hochstetteri), tīeke (saddleback), and hihi (stitchbird). The project's success is heard across Wellington; the songs of native birds like the kākā parrot and tūī are now common in city suburbs, a direct result of the safe breeding populations inside the sanctuary.