A no-fly zone has been imposed over part of Mangawhai to protect the country's most endangered birds, tara iti/fairy tern.
Helicopters, fixed-wing aircraft and microlight pilots flying over Mangawhai are jeopardising a tiny population of New Zealand's rarest bird, the fairy tern, according to the Department of Conservation.
Over three weeks last month, 31 aircraft were identified as breaching newly established restricted airspace over the wildlife refuge at Mangawhai Spit, directly north of Tara Iti golf course.
The population of fairy terns living on the spit, the main breeding ground of the birds, represented about a quarter of the country's total population of around 40, DoC biodiversity ranger Ayla Wiles said.
Wiles said the birds regarded low-flying aircraft as predators, and would potentially abandon their nests.
"It's very important that the restricted airspace is observed, to help prevent the species, possibly New Zealand's most endangered indigenous breeding bird, becoming extinct," she said.
"Pilots who ignore the restriction are not only in breach of Civil Aviation Rules but potentially also breaching the Wildlife Act 1953."
DoC was now recording registration marks of offending aircraft, and taking photos.
The restricted airspace, to 1000ft AMSL, is permanently active between October 1 and March 1. The restricted areas are on page 27 of the AIP Supplements 51/20 and in the Visual Navigation Charts.
Last month Foundation North granted $25,000 to New Zealand Fairy Tern Charitable Trust, to support its crucial work protecting the last 40 fairy terns alive.
In August the birds were given a boost ahead of its breeding season with the creation of new man-made shell nesting sites at Mangawhai and Papakanui, north of Auckland.
Tara iti typically build their nests, no more elaborate than a shallow scrape, on exposed, low-lying areas of shell-covered sand. Now they have 50 tonnes of locally-sourced shell that were delivered by the New Zealand Defence Force, which used the operation as a training exercise.
The operation was funded by the Shorebirds Trust and supported by the Tara Iti Golf Club, NZDF, local iwi Ngati Whatua o Kaipara, Te Uri o Hau and Ngati Manuhiri.
Birds' tough road to recovery
Fairy terns are critically endangered. The total population numbers fewer than 40 but that is a significant improvement on the three breeding pairs recorded in 1984, when the recovery programme began.
Last season, nine breeding pairs produced seven chicks.
The birds once nested on beaches around the North Island coast, but introduced predators, including feral cats, rats, stoats, ferrets and weasels, habitat loss and human disturbance have brought them to the brink of extinction.
They have nesting sites at Waipū and Mangawhai, in Northland, Pakiri and Papakanui, in the Auckland region.
The first eggs are laid in early summer and chicks to hatch around Christmas/New Year.
After breeding, the terns visit harbours and estuaries between Auckland and Whangārei, but mostly Kaipara Harbour.
Fairy terns also breed in Australia and New Caledonia.