Zealandia (wildlife sanctuary)

The sanctuary on the edge of suburban Wellington

Karori Wildlife Sanctuary is a protected natural area in Wellington, New Zealand, where the bio-diversity of 225 ha (just under a square mile) of forest is being restored. The sanctuary covers an area that was previously used as the water catchment area for Wellington, between Wrights Hill (bordering Karori) and the Brooklyn wind turbine on Polhill. The sanctuary, surrounded by a pest-exclusion fence, is a good example of an ecological island.

The sanctuary has become a significant tourist attraction for the city of Wellington and is responsible for the existence of a greatly increased number of sightings of species such as tui and kaka in city's western suburbs.

The sanctuary has inspired a raft of similar projects throughout New Zealand, with predator proof fences now protecting the biodiversity of many other areas of forest. Examples include: 98 hectare Bushy Park in Whanganui, the 7.7 hectare lowland podocarp forest remnant of Riccarton bush/ Putaringamotu in Christchurch city and perhaps most notably a 3,500 hectare tract covering an entire mountain thanks to the Maungatautari Restoration Project in the Waikato.

History

The whole valley was covered with native forest until European settlement of the area and the large fires in 1850 and 1860 that cleared the land to be used for farming. The lower reservoir, retained by an earth dam, was completed in 1873. Parts of the area continued to be farmed right up until 1906 when the upper reservoir, retained by a gravity arch dam, was completed. From this point, as the whole valley was a protected water catchment area for Wellington city, the slopes were revegetated with introduced trees and the native forest also began regenerating. After the dams were decommissioned in 1991 and 1998, the local Forest and Bird Society took the opportunity to pursue the formation of a unique, 'mainland island', wildlife sanctuary.

Pest-exclusion fence

A stretch of the fence

The most crucial aspect of the sanctuary is a pest-exclusion fence, specifically designed to exclude fourteen species of non-native land mammals ranging from deer to mice, that encircles the 8.6 km perimeter of the Sanctuary. Construction of this fence was completed in 1999 and all fourteen species of mammalian pests within the perimeter were then eradicated. This predator proof fence is of great conservation significance, being a world first.

Species to be excluded by the fence

Stoat running off after being unable to find a way through the fence.

• Black Rat
• Cat
• Deer
• Dog

• Ferret
• Goat
• Hedgehog
• Mouse

• Norway Rat
• Pacific Rat
• Pig
• 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).

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  Mesh size
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  Top cap detail
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  Footer

Example of small defect in fence mesh

In terms of its meeting conservation goals Karori wildlife sanctuary has met with considerable success thanks to the effective design of the encircling fence. As of 2006 the fence has been successful in excluding 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.

Restoration

Lower Karori Reservoir looking North-East

The flora and fauna in the sanctuary is 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 as Mahoe dominating. Members of the original flora that are missing from the site, or rare, include large podocarp species such as rimu, matai, miro, kahikatea, and totara, are being re-established. Northern rātā has also virtually disappeared from the valley and a number of seedlings have been planted. A wide variety of native trees, of benefit to native fauna, is already present including a mature colony of the New Zealand tree fuchsia, Fuchsia excorticata.

Species

Toutouwai, one of the many birds free to breed in the sanctuary and re-populate the surrounding environment

• Native birds that have been released in the Sanctuary since 2000 include:
  • Bellbird, New Zealand (Korimako) (Anthornis melanura)
  • Brown Teal (Pateke) (Anas chlorotis)
  • Kākā, North Island (Nestor meridionalis)
  • Little Spotted Kiwi (Kiwi pukupuku) (Apteryx owenii)
  • Pigeon, New Zealand (Kererū) (Hemiphaga novaeseelandiae)
  • North Island Robin (Toutouwai) (Petroica longipes)
  • Saddleback, North Island (Tieke) (Philesturnus carunculatus rufusater)
  • Scaup, New Zealand (Papango) (Aythya novaeseelandiae)
  • Stitchbird (Hihi) (Notiomystis cincta)
  • Tomtit, North Island (Miromiro) (Petroica macrocephala toitoi)
  • Weka, North Island (Gallirallus australis)
  • Whitehead (bird) (Popokatea) (Mohoua ochrocephala)

• Other native animals that have been released in the Sanctuary since 2000 include:
  • 70 Tuatara, Sphenodon punctatus, from Stephens Island were released into the Sanctuary in December 2005.
  • 100 Giant weta
  • 21 Maud Island frogs

• Other native species that are naturalised without needing transfers from outside the area include:
  • Birds
    • Fantail, North Island, (Piwakawaka) (Rhipidura fulginosa placabilis)
    • Grey Warbler, New Zealand (Riroriro) (Gerygone igata)
    • Tui (Prosthemadera novaeseelandiae)
  • Reptiles
    • Forest gecko (Hoplodactylus granulatus)
    • Skink

See also

• Pest-exclusion fence
• Ecological island
• Orokonui Ecosanctuary

External links

• Karori Wildlife Sanctuary website
• The predator-proof fence
• Meet the Locals (TVNZ) segment on KWS