The population of New Zealand’s endangered flightless parrot kakapo has increased by 25 per cent in the past year, bringing it up to 252 birds.

A good breeding season and success with artificial insemination were behind the increase in kakapos, the New Zealand Department of Conservation said.

Introduced predators such as stoats have nearly wiped out the kakapo as the birds cannot fly.

The problem has been exacerbated by inbreeding, very low fertility — only 50 per cent of eggs are fertilised — and because they only breed every two or three years when native rimu trees fruit.

The population of the kakapo, which is the world’s heaviest parrot, is now at its highest number since the 1970s.

“There were just 86 kakapo when I first started working as a kakapo ranger in 2002,” operational manager for the kakapo recovery program Deidre Vercoe said.

“That number was scary. Having a breeding season with 55 chicks feels like a very positive step.”

The program was established in 1995. It is a collaboration between the New Zealand conservation department and Maori tribe Ngai Tahu and uses volunteers to help with activities like monitoring the nests to keep them out of trouble.

Some birds have had to be rescued after getting stuck in the mud or after their legs were caught in trees.

Ms Vercoe said much of the success this season was due to the amount of fruit on rimu trees.

Success with artificial insemination this season was also key, she said. Eight surviving chicks were born from artificial insemination, compared to just five in the decade to 2019.

“Using artificial insemination has meant that some males, who had not yet naturally fathered chicks, are still represented in the future gene pool,” Ms Vercoe said.

“Artificial insemination can also help to increase fertility of the eggs laid.”

Reuters/ABC