The wild population of the world's rarest wading bird will be getting a boost with the release of 51 New Zealand black stilt today at the Mt Gerald Station in the Mackenzie Basin.

The birds will add to the 60 released into the Tasman Valley earlier this month.

The black stilt, kaki, remains on the verge of extinction, which until now, had fewer than 100 adults in the wild.

Conservation Minister Maggie Barry says the release will significantly boost the wild population.

"DoC works really hard on black stilt recovery, controlling predators in their braided river habitats and hatching and rearing chicks in aviaries before releasing them into the wild," Barry said.

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"This programme has helped build numbers in the wild from a low of 23 to more than 106 adult birds today."

The release was a collaboration between DoC, the Isaac Conservation and Wildlife Trust and a private landowner.

The released birds have all been bred by the Isaac Trust at its chick-rearing facilities in Christchurch.

"DoC's been working with Mt Gerald Station over the last two years to use the area's highly-suitable habitat for the release," Barry said.

"The station owner has been hugely supportive, letting DoC trap predators on station land, allowing daily access to the release site, and providing accommodation for onsite feeding and monitoring staff."

Almost all the black stilt wild population is restricted to the Mackenzie Basin, and only about 30 per cent of captive-reared birds survive to breeding age in the wild.

"Their only viable long-term future is to make their habitat predator free and clear from invasive weeds," Barry said.

"The survival rate has increased to 49 per cent in the past three years since DoC stepped up its predator control work in the Tasman Valley."

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DoC was also looking to introduce landscape-scale predator control in the Mackenzie, contributing to NZ's goal of becoming predator-free by 2050.