Russell Kiwi Protection started trapping stoats in 2016 and now had stoat traps spread over 2000ha of the 3000ha Russell Peninsula.
The group carried out intensive pest control – which entailed trapping for stoats, rats and possums – in a core area of 450ha, including the eco-sanctuary.
During the past three years more than 1200 traps and bait stations, each of which had to be checked every month, had been placed 50m apart throughout the sanctuary.
The most recent survey of the sanctuary had returned a result of "zero per cent" rats, Harwood said.
Species protected within the sanctuary included kiwi, weka, banded rail, fernbird, Australasian bittern, green gecko and kauri snail.
Last month's event was held to celebrate the volunteers' achievements so far and to let Russell residents know what was going on in their backyards.
The next phase of the project would be to re-introduce locally extinct species. The group's wishlist included the pōpokatea (whitehead), kākāriki, kākā, toutouwai (North Island robin) and the giant weta.
Money raised at the launch event would pay for a study examining the feasibility of bringing back pōpokatea.
Pōpokatea are the host species for the long-tailed cuckoo, so a successful re-introduction of the diminutive white-headed birds would also see the return of the migratory cuckoo.
Harwood hoped to keep expanding the area being trapped by 50-100ha a year, though that was dependent on funding from private donations and government agencies.
About 100 volunteers were involved in the project, including many landowners with properties ranging from 2ha to 100ha. Most of Russell's kiwi lived on private land so their role was crucial.
Some landowners paid the trust a fee, which was used to employ private contractors to carry out trapping, while others were provided with traps, bait stations and the necessary skills.
Harwood it was amazing how many landowners were keen to get involved.
"They benefit from living in an environment where pests are at super low numbers and the birds benefit from living in the area. It's an amazing project by locals for locals, to look after the local environment and the birds living here."