The world's fattest and only flightless species of parrot has just enjoyed an astonishing baby boom - and conservationists are thrilled.

Though they used to be one of the most common birds of New Zealand, there are only 147 adult kākāpō alive today.

The species was previously thought to be extinct until a small population was found on an island south of the country's mainland in the 1970s. Over the course of the following decades, their population incrementally increased from 18 birds in 1977 to 50 in the mid-1990s, according to The Guardian.

Kākāpō only breed every two to four years, when rimu trees produce fruit in what's known as a mast year. The last mast year, in 2016, saw a record 34 birds added to the population.

This month, however, scientists were delighted by the arrival of 76 new chicks - which is more than double the previous record number of hatchlings.

"It's absolutely huge, it's massive," Dr. Andrew Digby, a science advisor to the Department of Conservation's kākāpō recovery program, told The Guardian.

"In the last two seasons there have been huge quantities of fruit not seen for 50 years, so that's why all of the female kākāpō know it is time to breed, and actually started much earlier than usual, meaning some have now been able to nest twice."

A temporary hand-rearing facility was set up in Invercargill to help care for this season's most vulnerable chicks, providing a rare opportunity for people to see a kākāpō before they were returned to their predator- and pest-free island homes.

In previous years, public viewings were held over longer periods, but with the chicks and their mothers doing so well on the islands, the facility was not required for the same length of time this year.

"Kākāpō are [a cultural treasure] for all New Zealanders and we are so excited to share their success with the public this year," says kākāpō advocacy ranger Bronnie Jeynes.

"With all the rimu fruit available the chicks are really thriving on the islands this year. For the first time in recent memory we've been able to put three chicks in one nest! It's a hugely exciting time."

(WATCH this kākāpō's adorable happy dance in the video below)

I talk about the #conservation of two of the world's rarest and most unusual birds. Come for the weird bird videos and pics; stay for the science! #kakapo #takahe #NZ pic.twitter.com/qVhrRYzMiw

— Dr Andrew Digby (@takapodigs) October 12, 2018

I talk about the #conservation of two of the world's rarest and most unusual birds. Come for the weird bird videos and pics; stay for the science! #kakapo #takahe #NZ pic.twitter.com/qVhrRYzMiw

Fly The Good News Over To Your Friends By Sharing It To Social Media - Feature photo by Don Merton / Department of Conservation (NZ)