DOC aims to keep the islands free from pests including rats and mice in order to create a safe haven for native species living there. The call for public help comes after this week's completion of an operation to eradicate mice on Adele/Motuareronui, Fisherman/Motuarero-iti and Tonga islands.
People planning to visit the park’s Adele and Fisherman islands should check before going out on the water that boats, kayaks and all bags, containers, food and gear are clear of mice, rats, ants, spiders or other animals. All clothing, footwear and gear should be free of soil and plant material, including seeds and foliage.
A DOC operation in 2007 cleared mice from the islands, enabling them to become predator-free wildlife sanctuaries. Mice were found back on the islands in 2015 when mice numbers were high in the park due to heavy beech seed fall that provided more food and fuelled their breeding. This month’s mice eradication operation was carried out to restore the islands to being predator free.
DOC Senior Ranger Jim Livingstone says rat, mice and stoat incursions onto predator-free islands are an ongoing threat to the safety of threatened native species sheltered there.
“Rats and mice stowed away on visiting vessels can escape onto islands so it’s important that people check their boats, kayaks and gear for pests before they go.
“Rats are a threat to South Island robins/toutouwai and saddlebacks/tīeke that have been returned to Adele Island and to robins that have spread to Fisherman Island. Rats and mice threaten insects and lizards and, as they also eat seeds, they suppress re-vegetation. Mice can even eat small birds’ eggs and nestlings.”
Some predators can swim from the mainland to nearby islands. Islands have measures in place to counter invading predators, including traps to catch them and tracking tunnels that record footprints to detect them.
The mice eradication operation involved aerial applications of baits containing the rodent pesticide brodifacoum. The islands won’t be declared predator free again until two years of monitoring confirms their absence.
Public access is not allowed except by permit on Tonga Island to protect the island’s New Zealand fur seal breeding colonies from being disturbed. The seals can be viewed from vessels on the sea.