Department of Conservation (Doc) Te Anau Biodiversity ranger Andrew Smart said the hand-reared pateke were flown into the Arthur Valley area, near Milford, and released by Doc.
The transfer followed the successful release of 20 birds in the area last year, of which 14 survived - one of the highest survival rates for first-time captive release.
Mr Smart said Wednesday's release was made possible by the national effort of private breeders, conservation trusts, Ngati Wai, Ngai Tahu and local businesses supporting the project.
The pateke were prepared for release into the wild at Peacock Springs Wildlife Park, Christchurch, where they were taught to use supplementary feeders, banded and fitted with transmitters.
They were then flown to Queenstown before being taken by Real Journeys on a plane to Milford Sound, then helicoptered into the Arthur and Joe Valleys close to the Milford Track before release.
Mr Smart would be staying in the area for the next few days to provide supplementary food for the birds as they learned to forage and feed themselves in the wild.
"If survival rates are good more than 200 pateke could be released into Fiordland over the next five years.
"With only 2000 purebred pateke living in a wild state in New Zealand, this second release of pateke into the South Island is going to make a real difference," Mr Smart said.
Real Journeys Queenstown general manager Tracey Maclaren said supporting the release by providing the transfer flight free of charge, was considered extremely worthwhile with long-term benefits for native species in the region.
"We are conscious that we operate in a spectacular part of the world and we feel privileged to do so.
"Seeing the birds scuttle off into the undergrowth to settle into their new home was amazing after all the preparation and everyone will be monitoring their progress closely," Ms Maclaren said.
