identified the reservoir catchment as having special significance because it is a large self-contained habitat suitable for a wide variety of native plants and animals. In 1993 a feasibility study was carried out by the Wellington regional and city councils and after public consultation in 1994, the idea of a sanctuary was given the go-ahead. The Karori Wildlife Sanctuary Trust was formed in mid-1995 to implement the proposed 'mainland island' wildlife sanctuary. The project was featured in The Guardian in 2022. Pest-exclusion fence The most crucial aspect of the sanctuary is a pest-exclusion fence, designed to exclude fourteen species of non-native land mammals ranging from deer to mice, which encircles the 8.6 km perimeter of the Sanctuary. Construction of the fence was completed in late 1999 and all mammalian pests within the perimeter were then eradicated over a nine-month period. This predator-proof fence is of great conservation significance, being a world first design to bar all terrestrial mammals from mouse size up. Species to be excluded by the fence Black rat Cat Fallow deer Ferret Goat Hare Hedgehog Mouse Norway rat Pig Rabbit Possum Stoat Weasel The fence design was arrived at after trials with the various species to be excluded. Its main features are a small mesh size (to exclude animals down to the size of a mouse), a curved top-cap (to prevent animals climbing over) and an underground foot (to prevent animals burrowing underneath). In terms of its meeting conservation goals, the sanctuary has met with considerable success due to the design of the perimeter fence. The fence and ongoing monitoring have successfully kept the sanctuary free of all but the smallest species – the house mouse. It is thought that small defects in the fence mesh (damaged during construction) allowed mice to re-enter the sanctuary. Modifications to the fence have been considered in an attempt to permanently exclude mice, but meanwhile, mouse numbers are monitored and controlled. There have been occasional breaches of the fence by weasels and rats, these occasional incursions are not unexpected (for example resulting from storm damage bringing trees down upon the fence), and are picked up by on-going monitoring with tracking tunnels. Restoration The flora and fauna in the sanctuary are recovering from its pre-managed degraded state. Although the original primary forest has been regenerating since 1906, it is still only in the early stages of succession with small hardy trees such