KEY POINTS:
The survival chances of one of New Zealand's rarest birds has been boosted, with a chick on the Kaipara Harbour ready to fly for the first time in five years.
The New Zealand fairy tern, once widespread in the North Island, has teetered on the brink of extinction since the 1970s.
Today it has a total population of just 35-40 birds and is ranked as critically endangered.
The Department of Conservation said the chick's fledging - growing wing feathers large enough to fly - was an important development. Chicks were more likely to survive once they were at the flying stage.
The chick was hatched from an egg that did most of its incubating at Auckland Zoo before being returned to its parents to hatch.
Fairy terns nest on shell and sand banks just above high tide, which leaves them vulnerable to predators, disturbance by people, 4WD vehicles and dogs. They are also at risk from storms and very high tides.
"The birds cannot be transported to predator-free offshore islands because they are very particular about where they nest, and the chicks cannot be raised in captivity as they have to be taught by their parents to dive for fish," said DOC biodiversity manager Thelma Wilson.
"The population is slowly increasing thanks to greater protection and monitoring, but there is still a long way to go before they can be taken off the endangered list."
A team of wardens and volunteers has been trapping predators and preventing nesting birds from being disturbed by humans since September in preparation for the new arrival.
The fairy tern now breeds at only four nesting sites, at Papakanui Spit, Pakiri, Waipu and Mangawhai. Only 13 breeding pairs remain.
Fairy Terns
* One of the country's rarest birds with a population of 35-40.
* Smallest tern breeding in New Zealand, with adults about 250mm long and weighing just 70g.
* At risk from habitat depletion, predators such as rats, dogs, cats and hedgehogs, and recreational activities.
* Ranked as an endangered species and carries a Category A priority for conservation action.
