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At 76, Betty Rowe is no longer able to "lead the charge up the hill" to stand between her island's rare goats and the hunters' rifles.

But the veteran wildlife guardian will be doing whatever else she can to stop authorities culling her beloved Arapawa goats - a breed considered to be unique in the world.

Mrs Rowe is leading opposition to a planned three-week cull on Arapawa Island, in the Marlborough Sounds, by the Department of Conservation (DoC). The shoot is due to start next week.

DoC says it is required to stop the goats ravaging the unique native plant species on the island, but Mrs Rowe - who runs a wildlife sanctuary on the island - says sheep and cattle are the ones responsible.

"I just feel the whole thing has just been so unjust right from the beginning. This is why I have fought for [the goats], because they haven't got a voice have they?" Mrs Rowe said.

"If the goats are wiped out from the face of the Earth, it's not going to bother them. But it should bother us, because we allowed it to happen."

Conservation Minister Steve Chadwick has refused to comment on the cull, but DoC Marlborough Sounds area manager Roy Grose said it was necessary.

"It's not our policy to exterminate every goat on Arapawa Island, but we do want the ability to control the goats on a public reserve because the plants and vegetation are special to the island and unique to the Marlborough Sounds."

The goats were highly destructive, and for their preservation, they were best kept on private land, Mr Grose said.

Mrs Rowe has kept some of the island's goats on her 120ha wildlife sanctuary since she and her husband migrated from the US and first made their home on the island in 1972.

Within a year of living on the island she was writing letters to authorities to try to stop the killing of the goats.

In the past, supporters of the goats had stood between them and hunters "but at my age now I'm not prepared to lead the charge up the hill".

The distinctive Arapawa goats are believed to have descended from a pair of the old English species released by James Cook in 1773.

Recent testing by a geneticist from the University of Cordoba in Spain had proved that the Arapawa species was unique in the world, Mrs Rowe said.

While some had been taken off the island and herds established elsewhere in New Zealand and overseas, only a few hundred were thought to exist.

"These goats are part of our history," Mrs Rowe said.

"And we know now they are both scientifically and genetically important. They deserve more than a bullet."

Anyone who came across the Arapawa goats knew they were something special, Mrs Rowe said.

"People have come to see them who knew a lot more about wildlife than I ever did, and they also thought there was something very special and unique about them."

New Zealand's Rare Breeds Conservation Society, while concerned about preserving the goat, is not taking a strong stand against the cull - "simply because it's DoC's job to maintain the [island] reserve, and why would we pick a battle we would lose?" said society president Ross Fraser.

He said the species would survive, because Arapawa goat herds had been established elsewhere in New Zealand and overseas.