Battle for our Birds aims to reduce rat, possum and stoat numbers.
"The thing that concerns me is that they're spending billions of dollars on something they say works, when there are alternatives that can be used. I know these alternatives will cost a lot more initially, but will eventually be more cost-effective and a lot kinder.
"Once 1080 has seeped into our land and into our waterways, the clean-up bill will be huge."
Ms Armstrong spent eight years living on the West Coast of the South Island.
"When we first moved there and it rained, you would see tree-whistling frogs everywhere, the birds were so noisy and keas would get into rubbish bins at the back of cafes where I worked. Within the time I was living there they disappeared - they just weren't there anymore.
"What 1080 supporters fail to acknowledge is, that when those animals that eat 1080 die, they die a horrible painful death. Then the flies eat them before laying maggots which the native birds then eat - and then the birds die.
"You can say you're protecting our native birds but by default - you're actually killing them. I'm definitely pro-life and my concern for our plant is, we as humans, are the biggest pests of all."
Manawahe Ecological Trust chairwoman Frances van Elphen said while the Manawahe Ecological Corridor, which borders Rotoehu Forest, used labour-intensive trap lines to protect threatened species including kokako, it supported the use of 1080.
"The trust was formed to manage the community's interest in improving biodiversity in the corridor and we are fortunate we don't have to make the choice about 1080, the landowners do that," Ms van Elphen said.
"But we do support 1080 because, as of today, it is proven to be the most effective method of saving our endangered species. Hopefully in the future, we will have an alternative but, right now, it is the best we have."
Battle for our Birds will see work carried out at 34 sites covering more than 800,000ha, including the aerial drop on 2549ha of Rotoehu Forest.
The Government had committed $21.3 million from Budget 2017 to fund Battle for our Birds.