Deep in Auckland's Hunua Ranges, the annual kōkako nest survey is underway.
Kōkako chicks in the Hunua Ranges ready to be banded. Photo: RNZ / Sarah Robson
Years of hard work mean the kōkako population there is booming, with more than 100 breeding pairs.
With breeding season in full swing, a team of conservationists and rangers is keeping a close eye on how many chicks are hatching.
They do that by monitoring a sample of six nests.
When the chicks are around 13 days old, they will be removed from the nest, weighed and given identification bands, so the experts can track their progress.
Declan Morrison is part of the monitoring team and it is his job to go out and find the nests - a challenge in the thick bush of the Hunua Ranges.
"You follow them (the kōkako pair) for as long as you can, sometimes they will tend to hop between trees as opposed to flying, so you can follow them on foot.
"Once you see them enter a tree and stay there or visit a tree and you hear some small 'tuks', then you have likely got a nest there."
Kōkako can have two, sometimes three, nests each breeding season.
But they are not always in the most accessible places for humans, anywhere between five and 15 metres above the ground in the forest canopy, Morrison said.
"Some of them you can climb without a ladder, without ropes; others you need ladders, you need ropes," he said.
"If it is in a skinny tree or too high up, we just cannot bother and if that is the case, we have to follow the pairs after the chicks have fledged, to find out how many chicks they have had."
Nests sit high within trees, sometimes requiring ropes to climb to them. Photo: RNZ/ Sarah Robson
Kōkako ecologists Dave Bryden and Amanda Rogers are kōkako ecologists and called in to get to those hard to reach nests and help with the banding.
Before they go up to a nest, Bryden said they have to wait for the parents to fly off.
"When the parents have left to go get more food, we will nip up there, take the chicks out and we will put them in a black cotton bag.
"Then I will bring the chicks back on to the ground where Amanda and Declan can put the individual colour bands and their metal band on their leg, so that we can tell them apart from all the other kōkako."
Chicks are placed in black bags and taken down from their nests. Photo: RNZ / Sarah Robson
The parents are not too bothered by the disturbance of their nest.
And neither, really, are the chicks, Bryden said.
"The chicks, at this stage they are quite young, so we try and band the chicks when they are 13 to 16 days old.
"If the chicks are older than about 20 days, they are a little bit more alert, but at this stage they are pretty docile. They have got their eyes open, but they are pretty much away with the fairies."
Auckland Council senior ranger Miranda Bennett said the kōkako population in the Hunua Ranges has come a long way since the mid-1990s, when there was just one breeding pair.
"There has been quite an extensive pest control programme undertaken over the last 30 years and alongside that we have done translocation of adult birds into the Hunua Ranges from other populations to try and boost the genetics of our Hunua population."
At the last population survey in 2018, there were 106 breeding pairs.
The next survey is next year, and they're hoping that number could top 200.
In the meantime, the annual nest survey gives them a snapshot of what is going on, Bennett said.
"With six nests, and each of those nests, let's say they have two chicks, we can then say, if we have got over 100 pairs breeding, hopefully we are putting over 200 chicks into the population each year."
The next job, Bennett said, is to make sure those chicks reach adulthood, pair up and become breeders themselves.