A controversial 1080 operation in south Auckland's Hunua Ranges started on Sunday.
The $600,000 project will see 1080 poison dropped across 23,000 hectares in a bid to eradicate pests.
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"We're doing this so we can protect these taonga species that live in this signifcant forest," said Rachel Kelleher, the operation's lead.
The operation begins with a helicopter with a trickle bucket dropping small quantities over a width of 20 metres around an area boundary.
A second helicopter then extends that boundary with a larger spread, before a third fills the remaining area.
There are three helicopters in operation, which refuel and reload four times an hour. Each hour they cover roughly 2000 hectares of land, with real time GPS data collected to monitor where each helicopter is and where the bait is being applied.
But the operation has been controversial, taking a court battle to get it allowed.
Overnight, anti-1080 protestors continued their fight by apparently chaining together gates.
While the protestors weren't anywhere to be seen on Sunday, their mark had been left with anti-1080 messages spray-painted on local facilities.
"People have that right to protest and make their views known, but we're really concerned that our contractors remain safe," said Mace Ward, the general manager of Auckland Council's Parks, Sport and Recreation.
Some activists were concerned about toxins getting into the Auckland's water supply, of which 60 percent comes from the Hunua Ranges' four reservoirs.
To minimise the impact, two water reservoirs are being cut off at a time.
"Water quality testing commenced this morning, and that water will only be turned on when we get clear water results after a 48-hour period," said Mr Ward.
In 1994, during the first 1080 drop in the Hunuas, 11kg of bait was used per hectare. In 2015 it was 2.5kg, and this year it's down to 2kg.
Over a tennis court-sized area, four pellets will be dropped. Each pellet is 12 grams, and of that only 0.15 grams are toxic.
The park will be closed until the operation has been completed, and a medical officer has given it the all-clear. This could take a week.
A caution period will remain in place for months, with dog owners warned to be careful.
Newshub.
