The critically endangered kakapo, the world’s fattest parrot, is now closer to extinction after an unprecedented disease broke out, New Zealand scientists said Thursday.

The Department of Conservation (DOC) reported that one of the last kakapo populations located on a remote Codfish Island was hit by aspergillosis, a fungal respiratory disease. Seven parrots died, including two adults, while 36 others are still receiving special treatment.

This has been a huge loss for the entire bird species, which reportedly only has less than 150 fully grown birds left in the world.

“Aspergillosis is having a devastating impact on kakapo,” DOC said in a statement.

The setback sadly comes weeks after scientists hailed a bumper breeding season for the nocturnal birds, which were once thought to be extinct.

There was hope that the birds would continue to increase in population after 249 eggs have been laid thanks to the breeding program, which also fuelled expectations that at least 75 chicks could survive.

However, Auckland Zoo veterinarian James Chatterton said they are now more focused on saving the kakapo birds infected.

“It’s na unprecedented threat and we’re working really hard to understand why it’s happened this year,” Chatterton told TVNZ in an interview. “Our working theory at the moment is that it’s this year’s climate – it’s been a really warm year down south.”

Scientists and experts believed that the warm weather and crowded breeding nests on the island may have led to an abundance of aspergillosis spores.

The population of kakapos, which means “night parrot” in Maori, started to dwindle when pests such as stoats, cats and dogs hunted them. Breeding has also been hard for them, as they only mate every two to four years back when New Zealand’s native rimu trees are still full of fruits.

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