Cost of ridding island of stoats put at $200,000

Two stoats have been captured on Kapiti Island this year. Photo / Janet Howard

It will cost about $200,000 over two years to make sure Kapiti Island is predator-free again after a stoat was caught on Sunday, the Department of Conservation says.

It was the second stoat caught this year and it is likely the pests are breeding on the island, DoC biodiversity threats programme manager Colin Giddy said.

The stoats would have swum 5km to get to the island, off the Kapiti coast north of Wellington, or possibly travelled on a bit of driftwood or timber, he said, though this was not likely.

"The chances of one animal getting over there are actually fairly unlikely, but it still arrived - so the chances of two getting over there without a breeding population are even rarer again," he said.

"So I am thinking that there is actually a breeding population on the island."

The first stoat was caught in February.

It would take two years of combing the island and finding no more signs or animals to again class it as predator-free.

The process would involve dog searches, a full-time trapper, and cutting and marking biosecurity walking tracks where stoat traps would be placed, as stoats liked to travel on areas that were clear.

Mr Giddy said that by the end of June, DoC had already spent about $100,000 combing the island, after a staff member spotted the first stoat in November.

"It wouldn't surprise me if the end bill tops $200,000."

The stoat caught on Sunday was sent yesterday to Auckland-based laboratory EcoGene to do a DNA profile, which would reveal its gender and age, Mr Giddy said.

"The animal we have got is actually in good condition so they should be able to get some reasonable data from it."

Stoats have high metabolic rates, are very quick, and are designed for hunting. They eat often and travel large distances.

In New Zealand, stoats eat birds such as kiwi, kaka, takahe, kokako, tui and bellbirds.

"We have got a formidable enemy on the island, that's for sure," Mr Giddy said.

EcoGene, launched by Landcare Research in 2008, provides DNA services.

- NZPA