A total of 20 birds were brought from breeders around the country, including Kiwi Birdlife Park, in Queenstown, to Isaac Wildlife Trust's pre-release holding facility Peacock Springs, in Christchurch.
The waterfowl will be accompanied by three Department of Conservation (Doc) rangers and travel to Queenstown on a commercial flight before flying to Milford Sound with Real Journeys. From there, they will take a short helicopter ride to their new home in the Arthur Valley, close to the Milford Track.
There are fewer than 1800 pateke living wild in New Zealand, making them the rarest waterfowl species on the mainland.
The birds making the journey to Fiordland have been raised by the Department of Conservation's Pateke Recovery Group, with support from Real Journeys and Banrock Wines.
Doc biodiversity ranger Andrew Smart, of Te Anau, said more than 200 pateke could be released into Fiordland over the next five years.
"The first 20 is to make sure the trapping is adequate to protect them from stoats, and we believe it is. Next year, 40 to 60 birds [will be released], and a similar amount the following year, to create a self-sustaining community."
Each bird has been colour-banded, in order to identify an individual and its history. Permanent metal bands with identification numbers were attached as well.
The birds will carry 14g "backpack" radio transmitters for the first 12 months to make finding the small, usually nocturnal, creatures easier. If a bird is motionless for 24 hours, the transmitter switches to "mortality mode".
Doc biodiversity ranger Pete Kirkman will monitor the transmitters' broadcasts, check the pest traps and top up the supplementary feed three times a week for the first two months. He would return three days a fortnight over the winter, before resuming thrice weekly trips by September and the breeding season.
Mr Smart said pateke had evolved without night-time predators, and were vulnerable to introduced pests and changing habitats. If a bird was found dead, it would be transferred to Massey University to determine if death was by pest, predator or misadventure.
