The country's largest privately-owned conservation project has been allowed to show off kiwi to wealthy tourists without a permit, despite welfare concerns about the birds.
Complaints to the Department of Conservation (DOC) accuse the Cape Sanctuary in Hawke's Bay of putting tourist dollars ahead of kiwi health.
It comes as a report into the deaths of several little spotted kiwi two summers ago reveals they died from neglect.
A video of Sir Paul McCartney cuddling a squirming kiwi during a visit to Cape Sanctuary in December 2017 has been viewed more than 466,000 times.
But DOC admits the ex-Beatle should not have been allowed to hold the bird because only registered kiwi handlers can do so.
Furthermore, the sanctuary did not have a permit at the time to conduct what it called "kiwi advocacy tours", meaning it was in breach of the Wildlife Act.
The sanctuary thought it did have a permit, and DOC thought it did too, DOC Hawke's Bay operations manager Connie Norgate said.
"It hasn't been anybody in particular's fault and certainly not Cape Sanctuary, more so DOC."
She was not against kiwi being used for advocacy, especially in Sir Paul McCartney's case.
"Internationally that probably got us some good coverage for the plight of kiwi, which is a really cool thing.
"When we put it into context, kiwi are out there dying every day on public land where there isn't any management or pest control."
It wasn't until she started investigating complaints made against the sanctuary in February 2017 that she realised it did not have a permit.
Those complaints, obtained by RNZ under the Official Information Act, included concerns about high turnover of staff, the death of two kaka in cat traps in October 2017 and the death of nine Little Spotted kiwi in 2017.
There were also concerns that providing kiwi tours to paying guests "took precedence over other higher priority kiwi management".
The choice of birds used for tours was "guided by convenience rather than absolute requirement for a health check" and the tours were done at the expense of pest control in the little spotted kiwi sanctuary.
DOC finally issued Cape Sanctuary a 10-year permit on the 27 August, a few weeks after RNZ began making enquiries.
The Cape Sanctuary is situated on Cape Kidnappers, on three properties owned by American billionaire Julian Robertson and the Hawke's Bay Lowe and Hansen families.
It is not open to the public but guests at Mr Robertson's $2000-a-night Farm at Cape Kidnappers hotel can pay another $600 to accompany sanctuary staff carrying out health checks on kiwis.
RNZ understood these tours were often held when guests demanded them, even if it meant kiwis were handled more than they should.
Former Maungatautari Restoration Project kiwi manager Matthew Lark said the practise of kiwi tours was a contentious issue in the conservation community but the fault lay squarely with DOC.
"There is a generic culture in many North Island sanctuaries which enables people to do this. The rules around this are very lax. Many of them are not permitted, and many are not overseen or inspected by the department."
Concerns that kiwi tours at the Cape came at the cost of other species were lodged with DOC in October last year. That was after nine little spotted kiwi died between sometime between November 2006 and May 2017.
RNZ has been told at least 15 birds died - or nearly half the population - but they were not officially recorded because not all the birds were radio tagged.
A report into the deaths, written by consultant Steve Sawyer and obtained by RNZ, admitted radio monitoring of the birds was irregular between late 2016 and early 2017.
"At the same time the level of predator control at this site was not to the high standard expected within a site holding a range of critically endangered species and therefore did not provide adequate protection for little spotted kiwi."
The owners of Cape Sanctuary were unavailable to comment about the little spotted kiwi deaths, or the unpermitted tours, and referred questions to Mr Sawyer.