After the success of offshore islands in protecting our native species, mainland islands were introduced and have proved to be a successful conservation strategy. The process includes creating an ‘island’ by protecting an area of land, often with large-scale predator-proof fencing, eradicating all mammalian pests and restoring the native forest.
Why are mainland islands important?
New Zealand’s native species evolved in isolation from other regions for millions of years after the last land bridge to Gondwana was lost. Birds and insects dominated our ecosystems, and the only native mammals are 2 species of bat. As a result of this unique history, our native species have survival methods that are not adapted to predatory animals introduced by Polynesian and European settlers, and these predators have had devastating effects. For example, our native frogs had evolved a ‘freezing’ defence mechanism that is very effective against birds that hunt using sight but useless against mammals that hunt using smell.
Introduced mammals, including rats, cats, stoats, possums and mice, have caused the extinction of a number of our native animals and plants and restricted many others to predator-free offshore islands. Mainland islands are an opportunity to conserve populations of our native fauna and restore native flora that has also suffered due to land clearing and introduced species.
Establishing Orokonui Ecosanctuary
Orokonui Ecosanctuary - a new, 370-hectare mainland island - is a 20-minute drive from Dunedin. The Otago Natural History Trust manages the project.
The creation of the ecosanctuary has taken many years and involved a large number of people, including scientists, local iwi, government agencies and volunteers. The ecosanctuary now has a number of temporary and permanent staff that work alongside these other groups.
After public consultation, 3 important steps in setting up the ecosanctuary were agreed upon – pest eradication, restoration of the forest ecosystem and the reintroduction of native species.
- Pest eradication: A 1.9 metre high predator-proof fence surrounds the ecosanctuary. This highly specialised fence has a steel canopy to keep out climbing animals, like cats and possums, as well as a mesh skirt at ground level that stops burrowing animals. There is also an electronic surveillance wire to alert staff if anything breaks the fence. Once the fence was in place, 12 species of pest were eradicated from within the ecosanctuary, but regular monitoring is required to make sure the area remains predator-free. Staff use specially trained dogs and special traps to help in this work.
- Forest restoration: This work involves weeding out introduced plants and replanting the area with native species.
- Species reintroduction: In consultation with scientists, a number of species have been translocated to the area including kākā, jewelled geckos and tuatara. Some species are released freely into the ecosanctuary. Others are released into special enclosures and are closely monitored by staff.
The future for Orokonui Ecosanctuary
Now that plans and procedures are in place to monitor pests, enhance the vegetation and reintroduce species in stages, the staff have been able to look ahead to the future of the sanctuary.
An exciting development is the opening of the new Visitor and Education Centre. This centre is designed to be an environmentally sustainable building and to provide visitor facilities including interpretive displays. A teaching room is incorporated into the design, and school groups are hosted to learn about what the ecosanctuary is all about. A number of new tracks will begin at the centre, offering visitors the chance to explore points of interest in the sanctuary.
Otago Natural History Trust
PO Box 6425
Dunedin, New Zealand
Phone 03 482 1755
Find out more about Orokonui Ecosanctuary and read the latest news on their website.
Article and audio from Radio New Zealand Our Changing World featuring Chris Baillie and Elton Smith from the Orokonui Ecosanctuary
Find out more about mainland islands that are managed by the Department of Conservation.