This is possible because, within a kōhanga kiwi, the kiwi have bred and survived so well, the areas, usually islands or fenced sites, have reached their carrying capacity and new homes have to be found for young birds to avoid pressure for food and territories.
Kōhanga kiwi birds supplement existing wild populations, or are used to establish entirely new wild populations in places where kiwi would once have roamed. The potential for kōhanga kiwi to boost kiwi populations in habitat which is being protected but has a low density of kiwi is great, which is why they will play a key part in achieving a 2% growth in kiwi populations over the next few years.
Several kōhanga kiwi populations exist or are planned for brown kiwi. These include:
- Motuora Island, in the Hauraki Gulf, which has too many Northland brown kiwi for the island’s carrying capacity. Its birds established a new kiwi population at Tawharanui Open Sanctuary, and are now going to other sites, including Whangarei Heads.
- Maungatautari, in the Waikato, is home to western brown kiwi. At 3,400 hectares, it is the largest fenced sanctuary in New Zealand and has the capacity to provide hundreds of juveniles each year to regions such as Taranaki and Tongariro.
- Rotokare Scenic Reserve, in Taranaki, is another kōhanga site for western brown kiwi and hopes to start exporting birds in 2018 or shortly after.
- The Cape Kidnappers and Ocean Beach Wildlife Preserve Partnership, in Hawke’s Bay, will become a kōhanga kiwi for the eastern brown kiwi taxa, with birds going into the Kaweka Range.
Kōhanga kiwi populations are being established for rowi, on Mana Island off the Wellington coast, and on Motuara Island in the Marlborough Sounds.
Little spotted kiwi
Kapiti Island is the main kōhanga for little spotted kiwi and is one of the first in the country. Birds are regularly moved off the island, which is at, or close to, its carrying capacity. About 200 birds have been moved to other islands or to Zealandia, in Wellington. The Department of Conservation plans to swap birds between these populations to maintain genetic diversity.