Boaties urged to take care after DOC rangers trap huge rat on predator-free Tiritiri Matangi island

A huge rat spotted by a volunteer on Tiritiri Matangi island two weeks ago was caught in a trap at Hobbs Beach early this morning. Photo / File

A huge rat has been trapped and killed on a pest-free island in the Hauraki Gulf following a two-week-long hunt.

The Department of Conservation launched the mission to get rid of the rat after a Supporters of Tiritiri Matangi volunteer caught eye of the rat's tracks two weeks ago.

The volunteer had been checking tracking tunnels when they saw rat tracks on ink pads in two of the tunnels at Hobbs Beach.

DOC rangers Polly Hall and Andre De Graaf with the rat found in a trap at Hobbs Beach early this morning. Photo / Department of Conservation

The tip-off sparked a seven-day-a-week operation to catch the rat, which lasted two weeks.

Two pest detection dogs had been deployed to sniff out the rodent and DOC set 50 additional traps and at least 60 extra tracking tunnels.

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

The culprit was caught in a DOC 200 trap at Hobbs Beach and found by rangers at 6am today. It would be sent over to Auckland for scientific analysis.

Acting DOC Auckland Inner Islands Operations Manager John Galilee said the team was "thrilled" to have caught the rat.

"It posed a serious threat to the native birds and other native wildlife on Tiritiri Matangi," he said.

The island has been free of animal pests such as rats since 1993.

DOC ranger Polly Hall with the huge intruder. Photo / DOC

Gaililee said such pests posed a major threat to native wildlife, including takahē, kiwi pukupuku and kōkako.

Rats would eat eggs and chicks of native birds, as well as native lizards and weta. They would also eat seeds and flowers, depriving native birds of food.

Gaililee praised the work of his colleagues who helped catch the rat.

"It shows that our biosecurity systems to protect the pest-free islands in the Hauraki Gulf are effective," he said.

To prevent possible biosecurity threats in the future, Gaililee was bidding boat owners to make sure there wasn't a rat or mouse stowed away on their vessel whenever they're headed into the Hauraki Gulf.