Dozens of new kokako chicks have hatched in the Hunua Ranges this summer after an Auckland Council pest control operation in the area.
The 1080-based pest control programme has significantly reduced predators, and committee chair Councillor George Wood says the species monitoring results are promising.
"A little over a year ago we had a huge problem: the Hunua Ranges was teeming with rats and possums and our bird populations were being so heavily predated that no kokako were ledging and adult birds were being attacked," says Mr Wood.
When the programme began, rats were tracking at almost 92 percent saturation across the ranges and possum numbers were high, Auckland Council biodiversity manager Rachel Kelleher says.
Possums are now tracking between 0.25 percent and one percent, and rat densities between zero and 1.03 percent.
As a result 13 kōkako chicks have fledged from six monitored pairs, and some of these pairs are already nesting again.
Kokako are endangered slate-grey forest birds endemic to New Zealand.
The population, previously widespread, have been decimated by predations of possums, stoats, cats and rats.
"With this high success rate among the six monitored pairs, we estimate there could be more than 100 fledgings from the 55 pairs in the managed area," Ms Kelleher says.
"Hochstetter's frogs are still present, vegetation is recovering and we are about to undertake long-tailed bat surveys."
Mr Wood says the operational team created a relationship with mana whenua as a result of the project.
"The Hunua Ranges and Kohukohunui are very important to seven iwi with tribal ties to the area," he says.
The Hunua Ranges, southeast of Auckland, cover 250 square kilometres of hilly country, and contain 178 square kilometres of parkland.