Groundwork laid for pest project
Clearing mammalian pests from the largest of New Zealand’s subantarctic islands could be done, an expert says — but it’d require a hugelychallenging, decade-long effort costing about $80m.
Lying some 465km south of Bluff, within the wild and windswept Southern Ocean, the 46,000ha Auckland Island is the last in the group where pigs, cats and rodents still roam.
It’s home to some of the planet’s most stunning and unique biodiversity — but also pigs and cats that have devastated floral communities and driven the local extinction of most seabird species that once bred there.
Only about a dozen — including the Southern royal albatross — remain.
Mice, too, have hit the island’s invertebrate populations hard, while competing with native birds for food.
Since a five-year project succeeded in wiping out nearby Antipodes Island’s estimated 200,000 mice in 2018, the Department of Conservation has been assessing how Auckland
Island’s resident pests might be purged.
It’s something explored in a special issue of the New Zealand Journal of Ecology this week, which brings together nearly four decades of insights gleaned from successful operations run elsewhere in the remote archipelago.
Its editor, Professor James Russell, expected an Auckland Island programme, from mobilisation to mop-up, would take the better part of a decade.
“You’d need to take out the pigs with hunting, the mice with poison, then you’d turn to the cats, with a couple of years of follow-up and then de-mobilisation.”
DoC’s national eradication manager Stephen Horn, who led the Auckland Island research, said this week’s paper wrapped up a four-year investigation.
“An in-depth feasibility study was needed as this would be the largest and most complex multi-species island eradication attempted to date,” he said.
While DoC wasn’t positioned to start an operation there — funding was put on hold in April 2020 amid the Covid-19 crisis — Horn said the groundwork had now been done.
Clearing all of our uninhabited offshore islands — DoC manages about 220 larger than 5ha — remained one of several unfulfilled short-term goals of New Zealand’s wider Predator Free 2050 mission.