Rat footprints have been found on Tiritiri Matangi Island, in Auckland's Hauraki Gulf.

A rat pack has been assembled to hunt a predator lurking on pest-free Tiritiri Matangi Island.

A routine check of tracking tunnels on the island, in Auckland's Hauraki Gulf, revealed rat footprints on January 8.

The footprints were found on two of the monitoring cards inside the tunnels, showing a rat had been through them sometime in the period between New Year's Eve and January 7, a statement from the Department of Conservation said.

SUPPLIED Rats pose risks to native birds and lizards (file photo).

Two pest-detection dogs, Pai and Indie, were deployed to the island on Monday with their handlers to sniff out the rodent.

READ MORE:

* Auckland's war on rats is looking positive, experts say

* War on rats heats up on Waiheke Island

* Government sets target to make NZ 'predator-free' by 2050

More than 50 additional traps and at least 60 extra tracking tunnels have been put in place.

DEPARTMENT OF CONSERVATION DOC dog Indie hard at work on Tiritiri Matangi Island.

Tiritiri Matangi has been free of animal pests, including mice, since 1993.

It is home to a number of native birds including takahē, kiwi pukupuku/little spotted kiwi and kōkako.

There are also tuatara, wētāpunga and five types of native lizard on the island.

DEREK TEARNE Tiritiri Matangi is a haven for native birds, such as tūī.

DOC's Auckland inner islands operations manager Keith Gell said the response has been as rapid and comprehensive as possible.

Pai and Indie were still completing a sweep of the island, and it was not clear how long the effort would need to be maintained, he said.

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

SUPPLIED More than 35,000 people visit Tiritiri Matangi each year.

It was not known how the rat got to the island, but visiting boats were the most likely culprit, Gell said.

It was vitally important that boaties were vigilant about biosecurity measures when visiting islands in the Hauraki Gulf, he said.

"We need everyone who goes even near these taonga islands to play their part so we can preserve the treasures we have and not have to spend time and effort chasing rats that may have taken the opportunity to leap off a passing vessel."