After a bumper breeding season, the kākāpō has officially reached a record high at 213 birds.

It's thrilling news for conservationists who have battled to preserve the endangered native species.

"I think we owe it to the world to try and save these pretty amazing bird species," Dr Andrew Digby, Department of Conservation's (DoC) Kākāpō Recovery science advisor, told Newshub.

"They're one of the rarest birds in the world... They very nearly became extinct."

It's taken decades of work to get to this level; in the mid-90s, there were only 51 adults kākāpō.

"There are probably more kākāpō alive today than at any time in the last 70 years."

The official population isn't updated until chicks are deemed "juvenile" at 150 days old, Dr Digby said. This is because chicks often struggle to thrive.

Stella-3-B-2019 is the youngest chick from the latest breeding season and hit the milestone on Tuesday.

"Breeding seasons like the ones we've just had, they're the ones that really make the gains and increases in population," Dr Digby said.

"We want to get more kākāpō. We'll start to be a bit happy once we've got to around 500 birds and we've got some in a self-sustaining population."