Rat tracks discovered on predator-free Tiritiri Matangi Island in Hauraki Gulf

Rat tracks have been discovered on the predator-free island of Tiritiri Matangi which has prompted Department of Conservation to deploy traps and tracking dogs.

A rat has been discovered on an island sanctuary near Auckland which houses some of the country's most rare native birds.

Following routine checks rat tracks were found on Tiritiri Matangi, in the Hauraki Gulf, which is home to kiwi, takahe and tuatara among other protected wildlife.

Auckland Inner Islands operations manager Keith Gell said even a single rat could do significant harm to the island's "defenceless" animals.

Two pest detection dogs had been deployed to sniff out the rodent, Gell said.

"We have had Pai and Indie, two of the Conservation Dog Programme dogs, on the island since Monday [January 8] which, largely thanks to the support of Kiwibank, is twice what we would have had in past years," Gell said.

The Department of Conservation had also scrambled a team to the island along with more than 50 additional traps and at least 60 extra tracking tunnels being deployed.

Rat footprints were discovered on two of the island's monitoring cards inside the tracking tunnels sometime between December 31 and January 7.

It was not known how a rat got to the island, but visiting boats presented the "most likely" opportunity for the rodent.

"Is vitally important that boaties are especially vigilant about biosecurity measures when visiting the Hauraki Gulf islands."

It was not possible to determine how long the effort will have to be maintained.

"The operation will continue until we can be confident the island is once again free of predator-pests."