New Zealand has no native land mammals, apart from a few bats. 

Originally, it had about 60 lizard species, several frogs and a range of indigenous birds, many of them flightless.

Giant moas were the country’s equivalent of deer.

Around 800 years ago, Polynesian settlers arrived, bringing rats and dogs with them. The moas were hunted to extinction, the last ones being killed around the year 1450.

However, worse was to come. James Cook’s visit to the two large islands in October 1769 was followed by waves of European settlers.

They imported livestock, pets and pests, world, many of them lethal to native creatures.

New Zealanders want to turn the clock back.

Traps and poison air-drops are being deployed in a war against invasive species.

The control programmes are proving successful.

Predators have been eliminated from islands where they threatened native birds and the country has become the world leader in saving critically endangered species.

The kakapo and black robin, famously, were snatched from the brink of oblivion.

The struggle is to be intensified. New Zealand will mount ‘the most ambitious conservation project anywhere in the world’, declared prime minister John Keys on July 25.

The country, he hopes, will be free of rats stoats and possums, three of the worst alien offenders, by 2050.

This raises questions for us.

If the New Zealanders can mount such an operation, could we, living on a much smaller island, do something similar?

If so, which of our many aliens might we target and with what justification?

Deciding which species are ‘native’ may be straightforward in New Zealand but it’s more complicated here.

The list of our ‘aliens’, plants and animals introduced deliberately or accidentally, is expanding as spiders and insects arrive in ships’ cargoes. ‘Airport malaria’ occurs in Europe, showing that insects, such as infected mosquitoes, can travel by air.

Marine fish from warmer waters are visiting here.

Global warming is causing sea temperatures to rise, creating conditions which suit them.

The great white shark, found in the Bay of Biscay, may be here soon.

Having come under their own steam, these creatures might be deemed ‘native’.

However, they have availed of assisted passage, courtesy of global warming caused by us, so are they ‘alien’?

Our land environment, too, has changed almost beyond recognition.

Are species to be regarded as ‘native’ only because they were here long ago?

Creatures come and go, adapting to changed conditions, or failing to do so.

The black rat arrived and prospered until ousted by the brown one.

‘Natives’, such as the giant deer, have gone to the wall, unable to cope with change.

Red kites used to inhabit our countryside and perhaps our towns; they are here now only because we reintroduced them.

Pheasants red deer and a host of ‘coarse’ fish, introduced long ago, have been granted honorary citizenship.

Does it matter that much how a creature’s ancestors got here?

Most ‘alien’ species are not ‘invasive’; the dormouse, introduced to the midlands, isn’t doing any harm. Nor are ‘native’ species necessarily benign; bracken can take over an area as destructively as gunnera or Japanese knot-weed.

A quasi-religious sub-conscious notion seems to be at work. Is the ‘native’ versus ‘alien’ distinction the product of a ghostly unconscious bias?

Are we hankering after supposed halcyon days long gone, a primordial Garden of Eden in which god ordained that each species has its place?

Moving creatures around feels unnatural, even sinful. Despite Brexit and the barriers erected against refugees in eastern Europe, human populations are mixing as never before.

National and political boundaries count for less and less.

Similar processes are at work in the natural world.

Should we abandon the notion of ‘native’ versus ‘alien’ altogether and take a long hard look at a species’ supposed ‘invasiveness’ before rushing to judgement?


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