Three critically endangered kākāpō died in September, reducing the population of the world's heaviest parrot, and one of Aotearoa's most prized taonga, to just 244.

The flightless and nocturnal kākāpō was on the verge of extinction before a remnant population of around 170 males and females were discovered in 1977 on southern Rakiura Stewart Island.

From this population, and the last remaining captured bird from Fiordland - named after conservation pioneer Richard Henry - a ground-breaking recovery programme using remote predator-free islands was launched.

Graphic: Dr Andrew Peter Digby/DoC

The Department of Conservation programme has successfully halted the birds decline, although numbers remain critically low.

Two-year-old Madeline sustained an untreatable beak injury. Photo: Sarah Little/DOC

Last week a two-year-old named Madeline, a bird carrying valuable bloodlines back to Fiordland bird Richard Henry, had to be euthanised after being found with a severe and ultimately unrecoverable beak injury.

Earlier the same week Ōtepoti, a 5-year-old bird died after being found underweight and unwell.

Famous for being one of the first four kākāpō to be permanently returned to a mainland home - Sanctuary Mountain Maungatautari - Ōtepoti later made headlines after making two high profile escapes from his new home.

Ranger died at the beginning of September on Anchor Island. Photo: Jake Osborne/DoC

Ōtepoti was subsequently returned to his southern island home in June.

And at the beginning of September a five-year-old kākāpō named Ranger died on Fiordland's Anchor Island after being found dead following a suspected tree windfall.

Anchor Island has been an island sanctuary for kākāpō since 2005.