Lone rat tainting Rangitoto, Motutapu islands

A lonesome rat is tainting the pest free image of Rangitoto and Motutapu islands in Auckland's Hauraki Gulf.

It was detected during a routine check by Department of Conservation staff.

DOC spokesman Phil Brown says pest eradication will enable the island to become one of the country's largest sanctuaries for endangered wildlife.

He says rodents can have wide ranging and negative effects.

"That's why we've undertaken this operation to get rid of rats for Rangitoto and Motutapu in their entirety and why we're working so hard to get rid of this single rat we think is on there now," he says.

Mr Brown says 175 traps have been set to catch the rodent.

- Newstalk ZB