Whio, the native blue duck which is emblazoned on the $10 note became extinct in Egmont National Park in 1945.
But the recovery programme - which started in 1990 - has now established a sustainable population in the region.
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There are only about 2500 whio left in the wild, making the shy ducks much rarer than kiwi.
Department of Conservation biodiversity ranger Donna Worthy said Mt Taranaki was the perfect place to release whio.
"It's a really good place to have them because whio are torrid ducks.They like fast flowing, clean mountain streams. They like rapids, they're like the white-water ducks.
"So we've been releasing whio and we also have over 7000 hectares of protected area that's protected with over a 1000 stoat traps, because stoats are the main predators of the whio."
Ms Worthy said the six birds in the most recent release were bred in captivity near Christchurch at Peacock Springs and Orana Wildlife Park.
They then had to graduate from a "whio bootcamp" at the National Trout Centre in Turangi before being released.
"It's a big aviary that's big enough for them to fly around and it has a stream in the middle of it with flowing water.
"That gets them used to moving over rocky terrain, paddling in the fast water, getting used to rapids, foraging for their own food and, yeah, it kind of gets them tough enough to be released into the wild."
The first successful breeding in Egmont National Park was recorded in 2005 after trapping began in 2003.
There are now 33 pairs and a census last year put the total population in the park at 86.
Captive breeding coordinator for the recovery programme, Peter Russell, said in the early days of the project, most birds died after being released, but the corner had been turned.
"It's a numbers game, you've got to get the birds in here and once they are like now they're starting to breed and all of a sudden they're away by themselves.
"So I don't think we'll be releasing too many more into here, maybe some different bloodlines that about all every now and again."
Stratford Primary School pupil Ella Coulton was among of group a whio ambassadors who had been studying the whio and were on hand to witness the release of several whio into the Waiongana River on Mt Taranaki.
She was buzzing afterwards.
"It felt amazing and it was just really, really exciting and I was just jumping out of my skin to watch the release.
"Just seeing the ducks swimming around and trying to going up the rapids and being able to take photos of them."
So far this season 29 ducklings have been counted and DoC says it was hopeful that number would continue to increase.