Rat trapped and killed on pest-free island Motuihe in the Hauraki Gulf

A rat has been caught and killed on pest-free Motuihe Island in the Hauraki Gulf. Photo / File

Fears one of Auckland's treasured pest-free islands could be devastated after a rat was spotted have been allayed after the rodent was trapped by rangers.

The rat was detected on Motuihe Island in the Hauraki Gulf on Sunday night by a video camera set up by the Motuihe Trust to monitor kiwi pukupuku / little spotted kiwi.

The Department of Conservation launched an operation to catch it on Monday by setting traps, tracking tunnels and rat motels in the area the rat was filmed.

But it was a trap impregnated with rat scent, one of two sent from rangers in the Bay of Islands, that did the trick, DoC Auckland inner islands operations manager Scott Antcliff said.

The Motuihe invader caught on Friday morning. Photo / DoC

"This morning a ranger found the dead rat inside one of these traps.

"This is a great result by the team set up to catch the rat.

"This introduced predator posed a significant threat to native wildlife on pest-free Motuihe."

The rat caught in the trap "impregnated" with rat scent. Photo / DoC

DoC had used a rat-scented trap to catch a rat on pest-free Motutapu a year ago.

"So this lure is proving very effective in removing rats from pest-free islands," Antcliff said.

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

Motuihe has been free of rats, mice and other introduced pests since 2005.

The island provides a safe haven for threatened and at-risk native wildlife including kiwi pukupuku/little spotted kiwi, tīeke/saddleback. kākāriki/red-crowned parakeet, korimako/bellbird, tuatara and shore skink.

Antcliff said there was always a risk of a rat or other pest making it to a pest-free island.

"We're reminding people to ensure their boats, yachts and kayaks are not carrying a rat or mouse when they sail to Motuihe or other pest-free islands in the Hauraki Gulf Marine Park."