Twenty-three new parakeets have bolstered a Canterbury population of the rare birds.
On Thursday, the orange-fronted parakeets were released into the Hurunui South Branch.
The small parakeets, marked above their bills with an orange stripe, are critically endangered with an estimated 200 to 400 birds remaining.
RARE RELEASE: One of 23 orange-fronted parakeets/kakariki karaka released in the Hurunui River South Branch on Thursday, March 12. Image by John Kirk-Anderson
"Insurance" populations of the parakeets have been put on four predator-free islands: Chalky Island in Fiordland, Blumine and Maud islands in the Marlborough Sounds and Tuhua in the Bay of Plenty.
On the mainland, the birds live in just three Canterbury valleys: the beech-forested Hurunui, Hawdon and Poulter valleys.
Thursday was the first time the captive-reared birds were sent back into the Canterbury habitat.
The Isaac Conservation and Wildlife Trust in Christchurch bred the 23 birds. Department of Conservation (DOC) staff took them to their new home.
DOC conservation services ranger Simon Elkington said over a decade of pest control in the area allowed the release.
"There are a handful of orange-fronted parakeets left in the South Branch and the new birds are a step towards creating a self-sustaining population there," Ellington said.
The Isaac Trust breeds threatened native species including the black stilt, blue duck, Canterbury mudfish and Otago and grand skinks.
In November, 58 mohua were relocated from Chalky Island into the Hawdon Valley to boost the Canterbury population of the rare bird that features on the New Zealand $100 note.