An investigation is looking at what caused the illness, which caused the death of the three kiwis over a few months.

Tahi the one-legged kiwi, Wellington Zoos only resident kiwi, has died after a long illness.
He was the third kiwi to die at the zoo from a series of very similar symptoms.
Tahi had lived at the zoo for more than 15 years, unable to be released into the wild because of his missing leg.
Zoo chief executive Karen Fifield said it was a huge blow for zoo staff. He had been a part of the zoo longer than she had. Hes always been part of my life here.
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Tahi was well-loved by staff and the public, assisting keepers and ranger with advocacy around the species. (File photo)
Its been awful for all of us, to see him deteriorate, even with the very best of veterinary care.
He died on the veterinary table two weeks ago, although plans had been finalised to euthanise him due to his continued health decline.
Only a few months ago, two other kiwi due to be released into the wild became lethargic, disinterested in food, developed stomach ulcers, and died soon after.
The kiwi were all kept separate during their stay, so a full investigation into what could have caused this illness was ongoing. We will go to the nth degree to find out what went on, Fifield said.
Tahi, meaning one in te reo because of his one leg, arrived at the zoo after being found in an illegal leg-hold trap, otherwise known as a gin trap up in Northland.
At that stage he still had juvenile feathers, so the zoo team estimated he was 20 to 25 years old when he died.
He was the only permanent resident in The Twilight, Te Ao Mhina, which now sat empty, and would be closed for the forseeable future.
Manukura the white kiwi at Pkaha National Wildlife Centre also died recently. (File photo)
The zoo would be looking to introduce more kiwi, but not until environmental factors for the deaths could be ruled out.
The nation lost another famous kiwi recently, when Manukura, the female North Island brown kiwi who gained national attention for her covering of white feathers, died following surgery in December.
Vets performed an operation to remove an infertile egg that had become stuck inside Manukura, who lived at Pkaha National Wildlife Centre, but could not save the bird.
Tahi gained fame in the mid-2000s, when Weta and the Artificial Limb Centre fitted Tahi with a prosthetic leg.
A picture book was written on the events, called Tahi, One Lucky Kiwi, by Melanie Drewery and illustrated by John OReilly and Ali Teo.
Ali Teo and John O’Reilly designed and illustrated Tahi, One Lucky Kiwi based on Tahis true story. (File photo)
Despite the kind efforts, Tahi hated the leg. He kept trying to kick it off, Fifield laughed.
The public got to see Tahi often, the star of the show during kiwi talks in the enclosure. He was such an amazing advocacy animal, Fifield said.
One thing was for sure: There will never be another Tahi.