Motutapu, Rangitoto islands 'stoat-free' after 2-year invasion

Kendall Hutt
Source: 1News

Motutapu and Rangitoto islands in Auckland's Hauraki Gulf are now considered stoat-free after three of the elusive pests were caught.

The Department of Conservation had been working for almost two years alongside iwi Ngāi Tai ki Tāmaki to trap the three male stoats in efforts it has labelled as "challenging and frustrating".

DOC and Ngāi Tai ki Tāmaki were trying to stop the killer pests from undoing years of conservation work on the pest-free islands.

It is not known how much wildlife on the islands was killed during the incursion, but stoat DNA was detected on a kākāriki - New Zealand parakeet - and tūturuatu/shore plover.

READ MORE: 'Highly unusual' - Motutapu, Rangitoto islands plagued by three stoats

Conservation dogs also found several dead birds on scent trails.

The stoats forced the evacuation of Motutapu Island's population of 10 tūturuatu to a sanctuary and wildlife centre after three were found dead.

The tūturuatu is one of the world's rarest shore birds. With a population of about 250 birds, the survival of the endangered species relies on island biosecurity, breeding in captivity and predator-free islands.

The three found dead on Motutapu had been killed at night while incubating their eggs, causing a serious setback for the population which has struggled to become established on the island.

A view of Rangitoto Island from Motutapu Island.

To date around six of the evacuated tūturuatu have been returned to Motutapu.

The presence of a stoat was first detected on the islands in May 2020. It was believed to have swum from nearby Motukorea/Browns Island.

The male stoat, weighing close to 400g, was trapped months later in September. There were more than 600 traps across the islands at the time.

A second male stoat was trapped in January last year and the third and final male stoat was trapped in November.

In a first for DOC, this stoat had been lured into a trap, disguised in an artificial den, with a playback recording of baby stoats. The den had also been filled with bedding which smelt like a female stoat.

Billy Brown, a Ngāi Tai ki Tāmaki representative, said at the time the stoat had been "particularly guileful".

"Our team of trappers work in some of the most extreme conditions, especially on Rangitoto, so I want to acknowledge their hard work and perseverance. The islands and the taonga species they nurture have one less challenge to contend with."

A stoat.

DOC earlier said it was "highly unusual" to have three stoats on the islands in this space of time.

The islands usually only get one stoat every three to four years.

Dave Smith, DOC incident manager, told 1News after a conservation dog had checked the islands in April - the fourth since the third male stoat was trapped in November – it was decided the ongoing presence of a stoat was highly unlikely.

"Because of this the incursion response ceased. We currently consider the island stoat-free," he said.

The rāhui on Motutapu was also lifted. It had been in place since May last year, restricting access to the island and closing its campground.

Smith said given the three male stoats were adults when caught, DOC is confident there was no breeding on the islands during the nearly two-year incursion.

Despite this, a conservation dog will still be checking the islands twice a year, and a smaller network of traps are being kept baited for stoats.

Smith said an estimated $300,000 to $350,000 was spent on the stoat incursion.