After spending decades trying to eradicate rats from offshore islands, the Conservation Department has agreed to set up a sanctuary for a rare breed introduced by Maori.

The sanctuary will be created for kiore in two islands of Northland's Hen and Chickens group, in a move Ngatiwai say is aimed at protecting a species their ancestors introduced.

It is a policy about-turn by the department, which had worked since the early 1990s to eradicate kiore from offshore island reserves it manages.

The species was brought to New Zealand by Maori and was well established here by the 13th century.

In a new agreement with DoC the Ngatiwai Trust Board will manage the 24ha Mauitaha and neighbouring 2ha Araara as kiore refuges. However, the rats will be eradicated on the largest island in the group, Taranga.

Ngatiwai's Hori Parata has studied their impact on offshore islands for 30 years and doesn't consider them a pest.

He said the iwi considered the species significant because they were purposely brought here by tupuna, so tribal members were obliged to fulfil guardianship responsibilities.

The kiore's journey here was also the story of how Maori moved through the Pacific and that heritage was important to protect, he said.

Studies have traced DNA links to the Cook Islands and Tahiti.

DoC's Keith Hawkins said the islands were too far away from each other, and the rats too poor swimmers, to worry about them migrating the 7km distance to Taranga.

Kiore could have a devastating effect on 35 species of plants across the islands, native lizards, tuatara and birdlife. Shearwaters and grey faced petrels' eggs were easy prey.

"When the chicks start chipping they'll either take the eggs then or when the chicks are outside the burrow. They go for the fat. It's real silence of the lambs stuff," said Mr Hawkins.

But there were some benefits to saving kiore, which were thought to exist in small numbers across the islands. Populations on Mauitaha and Araara would be useful from a scientific perspective, to compare Taranga's recovery.

Mr Hawkins said the arrangement showed cultural and environmental priorities could be balanced in "reasonable ways".


Polynesian/Pacific Rat

* Introduced from Polynesia by 13th century.
* Diet of seeds, fruits, leaves, insects, lizards, eggs and chicks.
* Blamed for extinction or reduction of flightless beetles, giant weta, land snails, frogs, skinks, geckos, tuatara, bats.
* Pre-European Maori considered kiore a delicacy and their pelts good for making cloaks.
* Life span about a year.