Four young whio (blue ducks) have graduated from their early days at Pūkaha National Wildlife Centre to be released into the aviary at Tongariro National Trout Centre.

The captive-reared birds are taking the next steps on their journey to release, where they will bolster the wild population of this highly threatened duck.

Biodiversity ranger Karen Ardin says it's like high school for ducks, making sure they have the skills they need for the real world.

"They have three to five weeks with us, learning to swim and feed in fast-flowing water, giving them the best chance of survival when they are released."

With fewer than 3000 whio in the world, these four will be an important addition to the wild population.

Karen says ensuring a healthy release is a fulltime job.

"We're lucky to have dedicated volunteers from our community partners Project Tongariro – we couldn't do it without them."

Visitors are encouraged to take the chance to see these special birds close up over the next few weeks.

Credit: NZHerald.co.nz