New Zealand conservationists have begun a project to eradicate the 200,000 mice living on the sub-Antarctic Antipodes Island, more than 760 kilometres off the South Island.
The species, thought to have been introduced by fur seal hunters in the 19th century, pose a threat to native birds and invertebrates on the World Heritage-listed island.
Conservation Minister Maggie Barry said today it was the most challenging eradication project to be undertaken by the Government.
"The island is surrounded by rough seas and battered by Antarctic weather -- truly at the edge of the world -- and this expedition has posed extraordinary logistical difficulties."
Three helicopters, a yacht, a supply ship and a team of specialists have been mobilised for the operation, which will drop 65,500 kilograms of rodent poison over the 2045-hectare island from helicopters.
Eradicating the mice would remove the only introduced mammalian predator on the island and return the habitat to its natural state, Barry said.
The island provides a vital habitat for many seabirds, including albatrosses and is home to a number of land birds found nowhere else on earth, such as the Antipodes Island parakeet.
The project has been dubbed the "million-dollar mouse" programme because of a public fundraising campaign in 2012 to raise $1 million towards its cost.
It is also being supported by the private Morgan Foundation and WWF-New Zealand. The total cost is estimated at $5.78 million.