Normally the fight to keep Hunua's kōkako alive is waged in native bush. Last year its fate was fought for in an Auckland courtroom.
At times the Environment Court hearing into the legality of the operation got nasty.
Outside the court, protestors erected signs and held banners. In courthouse corridors Department of Conservation staff were photographed and threatened:
“I’ve got your photo. Your face is on Facebook. We will get you. Everybody will know you.”
Friends of Sherwood Trust, represented by lawyer Sue Grey, argued dropping “45 tonnes of deadly poison” into streams which fed into water storage dams was in breach of the Resource Management Act.
The Department of Conservation submitted the real risk was not to drinking water but of "serious and irreparable damage to the native flora and fauna of the Hunua catchment if the drop doesn't go ahead when planned".
The court threw the case out finding most of the material supplied by Friends of Sherwood Trust was opinion, rather than evidence. The Trust was ordered to pay costs of $40,000.
During September and October just in time for breeding, 1080 was dropped over the area.
Kōkako - the comeback kid
The 1080 drop and intensive pest control has seen pest numbers drop and kōkako numbers climb. The most recent census before last year's 1080 drop counted 55 breeding pairs.
Now there are 116 breeding pairs. Last season each pair produced an average of three chicks.
For the first time since conservation efforts began, Auckland Council thinks the public has a chance of seeing and hearing the birds. As part of Conservation Week, two guided walks are being offered and it’s hoped more will take place in the future.
It's something council staff are excited about. Kōkako are best known for their song. What would have been a common forest sound is now one few have experienced.
Chime-like, it's considered by many to be the pinnacle of New Zealand bird calls, putting tui to shame and giving the bellbird a run for its money. It’s hauntingly beautiful - and lengthy. Pairs sing to each other in hour-long duets, the longest duet of any song bird in the world.
For the first time in decades the duets are coming back.
In the mid 1990s there were 21 kōkako in the 23,000 hectare Hunua Ranges. Only one was female.
Auckland Council senior regional advisor fauna Tim Lovegrove explained being a kōkako mother is risky business.
"Essentially females are the ones which sit on the nest. When a predator arrives and climbs into the nest - like a possum or a ship rat - the female doesn't tend to get off the nest. She might try and defend it but she'll stay on it."
After years of predation the female kōkako population had been whittled down to one.
The path back has been slow, and the result of conservationists on the ground and lawyers in court. Kōkako are now classed as at risk, but recovering. However, recovery is “conservation dependent”. Without humans keeping introduced predators at bay, numbers would plummet.
As well as regular drops of 1080, volunteers spend around 3000 hours each year checking ground traps and bait stations along roughly 200 kilometres of bait lines.
Lovegrove said the knockdown effect of last year's 1080 drop will wane.
"In the first summer it gives unbelievable protection, you almost don't need to put bait in the bait stations. The second summer numbers start to creep up, especially the rats. The third season you start running into higher rat numbers. The fourth season you need to repeat the 1080 drop."
By 2022 the predators will be likely be posing a threat.
Lovegrove expects unless a better tool is found, 1080 will be needed again.
To date Auckland Council has not received any of the court-awarded costs from Friends of Sherwood Trust.