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Fight to wipe out alien species

BBC Wildlife

September 2025

New Zealand public urged to help rid country of destructive species from overseas

IT HAS BEEN DONE ON LUNDY (SIZE: 4.45km²), Ruapuke Island (16km²) and South Georgia (3,500km²), but now conservationists want to eliminate nonnative, invasive predators from much, much larger sites: New Zealand's North (114,000km²) and South (150,000km²) Islands.

No one denies that it is an admirable ambition because alien, mainly European mammals have had a devastating impact on New Zealand's native fauna, with an estimated 25-30 bird extinctions, plus losses of reptiles, amphibians and insects.

So when the government in Wellington announced it would aim to eradicate three species of rat, as well as stoats, weasels, ferrets and brush-tailed possums, the entire world took notice. It was bold and aspirational - but could it be done? And was it actually a good idea?

A big part of the new approach, explains Jessi Morgan of the Predator Free New Zealand Trust (generally shortened to PFNZ), is that the drive to eliminate these unwelcome species involves community participation all around the country.

New Zealanders have a long history of being involved in conservation projects such as planting trees or looking after local reserves, and they wanted to know how to get involved. “Conservation moved from something done in our national parks and the bush to something we do in our cities and in our backyards," says Morgan.

Most countries have non-native wildlife but New Zealand has suffered disproportionately. That's because for millions of years, its birds and reptiles (its only native land mammals are three species of bat, one of which is probably extinct) evolved without any terrestrial predators. Many of the islands' most iconic species - kiwis, for example - are slow, flightless and largely defenceless in the face of even a small carnivore such as a stoat.

These introduced predators mainly came with colonisation in the 19th century.