Eight of the rarest type of kiwi have died from a respiratory tract infection at Wellington Zoo.
The young rowi, who had been living on predator-free Motuara Island in the Marlborough Sounds, were being treated for a type of worm at the zoo when they started showing signs of respiratory problems, thought to be caused by the bark they were being housed on.
DOC's Franz Josef biodiversity manager Jo Macpherson said the bark was regularly used by the zoo with no adverse effects, and the birds' weakened immunity had made them more susceptible to the illness.
The respiratory tract infection was caused by a fungus called Aspergillus spp which is common to the natural environment but can cause severe damage to the lungs and air sacs in birds.
''This is an extremely rare and unfortunate occurrence and has come as a great blow,'' she said.
Ms Macpherson said it a difficult disease to treat and the zoo and DOC staff are devastated by the loss.