Duncan Toogood, acting operations manager for DoC's Manawatu District, said the aerial 1080 dropping operation had been planned to give maximum protection to the highly valued species in the area.
"This operation will offer a fighting chance to Ruahine populations of at-risk species, such as whio, kiwi, giant land snails, robins (toutouwai), kakariki, bats (pekapeka), red mistletoe, dactylanthus, and Turner's kohuhu."
Beech masts provided a short-term bounty of food for introduced predators, driving them to higher numbers than usual, he said.
"This increase in animal pest numbers could lead to the loss of our threatened taonga species. Once the seed runs out, these predators will look for other food sources - our native species."
To reduce rat, stoat and possum numbers, cereal baits containing biodegradable sodium fluoroacetate (1080) would be dropped over the more than 30,000ha, he said.
The aerial drop would take place over two days, some time after September 6, with the exact timing reliant on weather conditions.
First, non-toxic prefeed baits will be dropped over the entire block, at least one week before the poison drop.
Then poison baits will be aerially sown at 2kg per hectare, at the next available weather window. After the operation there will be a withholding period of up to eight months, meaning hunters are advised not to take meat from the area.
Without predator control, Toogood said only 5 per cent of kiwi chicks hatched in the wild will make it to their fourth birthday, and for every three breeding pairs of whio, only two ducklings will make it to fledging.
"Pest control is an ongoing battle. Every year we face new challenges that put our vulnerable native species at risk. To ensure the survival of these taonga, we need to act.
"Aerial 1080 is the most effective large-scale pest control tool we currently have and monitoring shows it's successful in protecting vulnerable species and allowing birds to produce more chicks to sustain and build their populations."
Community-led ground-based predator control was also helping to protect northern Ruahine taonga species, he said.
"There are four community trapping initiatives within the Northern Ruahine Battle for our Birds treatment area, servicing more than 1000 traps.
These volunteers make a valuable contribution to protecting the taonga species of the Ruahine Ranges but trapping cannot keep up with the boom in predator numbers that follows a beech mast, especially over such large-scale, difficult terrain."
The northern Ruahine operation is one of 34 Battle for our Birds predator control operations taking place across the country this year that together cover about 800,000ha, or 10 per cent of public conservation land.
Battle for our Birds is a nationwide predator control programme that supports DoC's goal of protecting threatened species and making New Zealand predator free by 2050.
NZ Deer Stalkers Association president Bill O'Leary said it was opposed to 1080 but understood DoC's commitment to protecting native birds.
The association had negotiated with DoC to reduce its effect by using smaller pellets and dropping 1080 at certain times of the year when more feed was available for deer, he said.
"We also understand there are a lot of people out there who are opposed to the use of toxins."
Dogs in particular are highly at risk of dying from 1080. The risk to dogs from poisoned carcasses lasts until carcasses have completely rotted, which can take more than six months.
