The Department of Conservation believes another stoat has managed to find its way onto a pest-free island in the Hauraki Gulf.

A member of the public reported a possible sighting on Motuihe Island at the weekend, only two weeks since a stoat was caught on Motutapu Island.

DoC Auckland Inner Islands Operations Manager Keith Gell is inclined to believe the report.

"The person who sighted it was pretty confident he did sight a stoat and we've had a few eggs go missing from some of out traps as well so we are a little more confident that there is one there."

Gell says it is unusual to have this many sightings.

"It is worrying, you know stoats can swim, they are very strong swimmers. Whether it's the summer we've had, we're working through that just trying to figure out the 'why', why we''re getting all these incursions."

Gell says the sniffer dog team will arrive at Motuihe Island on Monday week, before heading to Browns Island, then Rangitoto and Motutapu.