Researchers at Auckland Zoo are trying to understand a virus that is affecting native parrots and spreading through the country.
Beak and feather disease was found in kakariki parrots in 2008 and this year has turned up in the South Island for the first time.
The virus seemed to be confined to introduced parrots until it appeared four years ago in the Hauraki Gulf.
In January, it appeared in Fiordland in a second species of kakariki, which is also known as the New Zealand parakeet.
Tests are being done on Tiritiri Matangi Island in the Hauraki Gulf to measure the spread and damage of the virus.
Researchers say there is a risk it could spread to other native parrots, such as kea, kaka and the critically endangered kakapo.
So far no kakapo have contracted the virus.
Auckland Zoo vet Bethany Jackson says its effects vary from species to species and by age.
She says it can cause some birds to lose feathers or die very quickly, while others recover completely.
