Islands are critical for endangered species for the simple reason that the barrier provided by water prevents predators from reaching them. Where predators such as rats are present, techniques and technology now exist to eradicate them, thereby rendering islands safe.

The Department of Conservation has about 220 offshore islands in its care. These include the sub-Antarctic islands, and numerous islets and rock stacks. Department staff are acknowledged world experts at exterminating unwanted predators from islands, and are now able to tackle very large islands.

Four such projects have been made possible by $3.2 million funding from the New Zealand Biodiversity Strategy. Predator eradication programmes have commenced on sub-Antarctic Campbell Island (11,300 hectares), Tuhua/Mayor Island (1280 hectares) in the Bay of Plenty, Hauturu/Little Barrier Island (3083 hectares) in the Hauraki Gulf, and sub-tropical Raoul Island (3177 hectares) in the Kermadec Islands group.

So far, rats and cats have been successfully eliminated from Tuhua/Mayor Island. Indications are that the Campbell Island operation, begun in July 2001, will achieve its goal of eliminating the Norway rats that have wrought havoc among the island’s seabirds. On Raoul Island poison baits were spread from the air in July 2002, and follow-up monitoring is expected to confirm success by 2004. Planning and preparation for the Hauturu operation is under way.

Biodiversity strategy funding is also benefiting the network of other predator free islands throughout the country through improved contingency planning to prevent rodents from reaching islands, and from better management of any invasions that do occur.

Work has included the laying of bait stations at departure and entry points, such as wharves and beaches, and the renovation of rat-proof store rooms where supplies are sorted and packed for island expeditions.

The Department of Conservation’s website has other detailed information about offshore islands.