Becoming too inbred is one of the threats to New Zealand's native birds highlighted in a new report.
Environment Commissioner Dr Jan Wright's latest report is aimed at highlighting the desperate situation New Zealand's birds are in, and warns urgent action is needed to save them.
In order to survive, birds need genetic diversity, Dr Wright says, using one kokako on a Hauraki Gulf island as an example.
"On Tiritiri Matangi, a kokako named bandit is consorting with his grandmother," she says.
"This may be a happy relationship, but it is unlikely to be a healthy one."
Inbreeding happens because bird populations are small and isolated, often on offshore islands or small chunks of native bush.
Dr Wright says the solution is place permanent protection on large tracts of habitat, which will cost a lot of money.
She recommends a 'nature' border levy paid by tourists as a new source of funding.
Tourism Industry Aotearoa CE Chris Roberts disagrees.
"We support 99 percent of the report, but the recommendation of the border tax is just yet another in a long list of sectors who want to tax our visitors," he says.
"This is passing the buck. Our birds are endangered because of the actions of New Zealanders, our visitors won't endanger those birds."
A third of New Zealand's native birds are at risk of extinction, including the world's only alpine parrot, the kea.
Other at risk birds are the wrybill, the only bird in the world with a beak that curves to the side, and the whio, a duck which paddles through rough water like a whitewater kayaker.
Dr Wright also said that feral cats need to be brought under control.
"These bird killers now almost certainly number in the millions in the countryside and along forest margins."
The report gives seven recommendations to the Government, including research into genetic modification as a way to control pests.
"Ninety-three of our bird species are found in no other country," Dr Wright says.
"We must look after them. Our birds need help not only in national parks, but on farms, along rivers and coasts, and in cities. This is a battle for all New Zealanders."