Orokonui Ecosanctuary has reached another milestone in its fight against pests - it has finally eradicated the rats and mice.
While the ecosanctuary, which is surrounded by a predator-proof fence, had eradicated 14 pest species, including possums, goats and rabbits, since it closed the fence in 2007, low numbers of rats and mice had continued to be detected, general manager Chris Baillie said.
While many reintroduced species could survive adequately with rats and mice levels at below 5%, the ecosanctuary had always aimed to eradicate them completely, she said.
The 1100 tracking tunnels and 130 traps placed 50m apart over lines 50m to 100m apart that cross the whole sanctuary had been empty for the five checks made since mid-August.
"This result means we are one of the very safest forests in New Zealand and it enables us to contribute to the survival of rare and vulnerable flora and fauna."
Eradicating the rats and mice had required an intensive effort by conservation manager Elton Smith and ranger Kelly Gough in maintaining the fence and monitoring during the past three years, she said.
"Mice have very small home ranges and baby mice are able to get through spaces of 7mm in the fence and culverts. They're smart and very tricky to eradicate."
A new buffer zone had been established outside the fence to provide a "first line of defence" against the re-entry of the pests and to reduce pressure on the specialised fence.
"Already it has caught two weasels, one stoat, four rats, seven mice, 11 hedgehogs and 10 baby rabbits."
