The Department of Conservation is planning to begin aerial applications of nontoxic pre-feed baits in Waitutu Forest, in the Fiordland National Park, today if weather conditions permit.
The nontoxic cereal baits would be aerially applied over 25,000ha of the forest as part of the Waitutu Restoration Project.
Doc ranger Colin Bishop said the pre-feed baits, which were brown in colour and cinnamon lured, were applied before toxic 1080 cereal baits to attract possums.
The pre-bait feeds were an essential part of the operation, ensuring possums would get used to the baits by having them dropped at least five days before the toxic drop.
The area's increasing possum population had a significant effect on the forest's unique biodiversity, including native species such as mistletoe and kaka, Mr Bishop said.
"Possums are changing the forest. It's vital we protect this iconic and unique ecosystem from the increasing pressures of these introduced pests."
The aerial application of 1080 was part of the department's restoration project which included ground control and ongoing monitoring of the area.
Mr Bishop said the department was using the most efficient and cost-effective tools available to ensure the area was protected for the future.
A range of control and pesticide options had been investigated: the aerial application of 1080 in Waitutu was up to 40% more cost-effective - the equivalent of 7000 to 10,000 more hectares covered - in comparison with using only ground control.
The treatment area was less than 2% of national parkland and would see 25 tonnes of nontoxic pre-bait feed aerially applied to the area, at a sowing rate of about 1kg per hectare.
