Last month, helicopters dropped 1080 bait on a 6500ha trial area in Stewart Island as phase one of a Department of Conservation( Doc) and Zero Invasive Predators (ZIP) operation to kill feral cats endangering the pukunui southern dotterel population on the island.
The full operation is set to cover about 43,000ha of the island
Bait with deer repellant was dropped in the hunting blocks within the trial area.
Stewart Island resident Mike Douglass spent four days walking the Rakeahua Valley to see the results of the poisoning.
He found three dead white-tailed deer in the hunting block where deer repellant was used, possums, rats and a tomtit.
He sent stomach contents and muscle samples to Manaaki Whenua Landcare Research for testing.
The information, which included the Manaaki Whenua Landcare Research report, also included background to the report and a question and answer section written by Doc staff.
It stated that small numbers of dead tomtits were occasionally found after 1080 operations because some peck at 1080 baits on the ground.
The amount of 1080 in the Stewart Island tomtit muscle tissue was consistent with tomtits tested in 1080 drops at other sites, it said.
Doc Southern South Island regional operations director Aaron Fleming said while tomtits were found dead after predator control operations, there was no evidence from past monitoring the tomtit populations were impacted.
The far bigger risk to the species and other vulnerable native wildlife came from rats, feral cats, and possums, Doc said. Removing these predators allowed tomtits to breed with reduced predation pressure.
Doc staff had not noticed a decrease in birdsong in the trial area, he said.
After the dead deer were found ZIP operations director Duncan Kay said the operation was an opportunity to measure the effectiveness of deer repellant in reducing the impact of 1080 on white tailed deer on the island.
"It is acknowledged that deer repellent is unlikely to prevent all deer deaths."
Protect Rakiura Trust administration team member Furhana Ahmad said the group expected to see more native wildlife by-kill as a result of the aerial 1080 drop.
There was little monitoring done on the wildlife numbers prior to the 1080 drop so it would be hard to determine the impact of the poisoning, she said.
ZIP monitoring of pests had taken place at ground level which had shown a lot of kiwi but not the birds that lived in the trees, she said.
It would also be hard to find the bodies of the dead wildlife to know how many had died, she said. Phase two of the operation where bait will be dropped on an enlarged area was planned for later this month.
