The stoat was found by a DOC ranger checking traps on Motutapu, as part of the ongoing biosecurity work to keep the island free of introduced predators.
The trapped stoat was found near Emu Point on the Motutapu side of Islington Bay, which connects Motutapu to Rangitoto.
Stoats are 'public enemy number one' for native birds. They're voracious and relentless hunters, eating eggs, chicks and adult native birds. Stoats are also prolific breeders.
"A stoat poses a massive risk to threatened and at-risk native birds on Motutapu, including kiwi, takahē, tīeke or saddleback, shore plover or tūturuatu, pāteke and kākāriki," says DOC Auckland Inner Islands Operations Manager, Keith Gell.
"The good news is that our biosecurity system, to detect and catch predators that make it to our pest free islands, works really well."
"The disturbing news is that a stoat managed to travel to pest-free Motutapu," says Keith Gell.
The stoat, killed instantly by the trap, has been sent to Auckland for DNA analysis. "We're hoping this analysis may indicate where the stoat came from," says Keith Gell.
"The stoat may have hidden on a vessel that travelled to Motutapu or sailed near the island. Or it may have swum to the island."
"This reinforces the need for boat owners to make sure there isn't a stoat, rat or mouse, stowed away on their vessel, whenever they set out to sea in the Hauraki Gulf," says Keith Gell.
Fullers and 360 Discovery, who run a ferry service to Motutapu and Rangitoto, have a pest free warrant from DOC. The warrant shows that Fullers and 360 Discovery meets DOC's biosecurity standards for sailing to and past pest-free islands in the Hauraki Gulf.
Since the dead stoat was found, all the traps designed to catch stoats - on Motutapu and Rangitoto - have been rebaited with fresh rabbit meat and fresh eggs.
"This is the bait we used to lure the stoat into the trap, so we know it's effective in catching these predators," says Keith Gell.