For more than a century, the dominant narrative in New Zealand has been that introduced species are ‘pests’ – invaders to be eradicated at all costs. Forest & Bird, DOC, and other agencies still promote this eradication mindset. Yet it is increasingly being questioned - after all, introduced species are now part of our landscapes, ecosystems, and cultures. They are not going away. It’s time to accept that, like us, they are here to stay.

As ecologist Dr. Jamie Steer put it in an RNZ interview, “These species are here, they are ours, they are part of our biodiversity.” (1) The challenge before us is not elimination, but how we live alongside them.

From waka to ships: how species first arrived

The story of introductions begins long before Europeans arrived in New Zealand. When the first waka reached these shores, Polynesian voyagers brought species central to survival and culture. The kiore (Pacific rat) and kuri (dog) provided food, companionship, and fur. Kūmara and yams offered reliable crops. Even the pūkeko, a bird we now see in wetlands across the country, was introduced at this time. (2)

Centuries later, waves of European settlers arrived with their own precious cargo. Sheep, cattle, pigs, and goats were essential for farming. Horses provided transport and labour. Deer, trout, and tahr were deliberately released for sport and hunting. Hedgehogs and rabbits followed too, some accidentally, others through acclimatisation societies who proudly stocked New Zealand with ‘home comforts’. (3)

Moving species is part of being human

The global history of people is also a history of plants and animals moving across oceans and continents. Wherever humans travel, they carry species that offer food, fibre, medicine, or companionship. Early Polynesians did it. Europeans did it. Migrants today still do it.

This movement is not a quirk of colonisation – it is human nature. And ecosystems, too, are not static. They evolve, adapt, and re-balance over time. New species appear and others less fortunate disappear. Nature is always in flux. Yet New Zealand conservation often clings to a romanticised snapshot of a pre-human landscape, as if ecosystems could be ‘reset’ to a frozen point in time.

The overlooked benefits of introduced species

Public conversations often focus on damage; yet introduced species can provide real value. Some examples of how we value these species:

Cultural connections: Deer hunting and trout fishing are part of Kiwi identity. Generations of families have bonded over hunting trips and weekends fishing on the river.

Economic lifeblood: Farming introduced animals such as sheep and cattle remain the foundation of our economy. Possum fur supports a sustainable cottage industry. Trout fishing attracts international anglers and tourism dollars, and deer provide significant economic and recreational value to local and international markets.

Ecological roles: In some cases, introduced species fill gaps. Gorse, while frustrating for farmers, acts as a natural nursery for regenerating native forests. (4) Its dense spines also provide cover for small birds against predators. Introduced birds spread seed, while rats and possums eat and help prevent troublesome wild conifer seeds from germinating. (5) (6)

Social value: Dogs, cats, horses, and even birds are our companions and working friends. Garden plants and trees shape the beauty of our towns and backyards, and mark the seasons in glorious colour.

Even so-called ‘pests’ are not always villains. In Queenstown, ferrets – long demonised – are being used to control exploding rabbit populations. (7) This experiment shows how introduced species can be part of the solution - not only problems. Using animals to help in the control of unwanted animals isn’t new. Dogs are used regularly for rat, possum, pig, and rabbit control - and many farms and rural properties have cats to manage mice and rats. Other animals were brought here with that exact purpose, albeit naively.

Possums, deer, trout, and gorse: stories of complexity

Possums: villains or a valuable resource?

Possums are heavily targeted in eradication campaigns, yet they were brought here as an economic asset. Their fur is prized for its warmth and sustainability and possum meat is highly nutritious and used in pet food. With proper population management, they need not be a symbol of destruction, but recognised for their economic and cultural value.

Deer: treasured game animals

Introduced in the 19th century, deer are now deeply embedded in our hunting culture. They are also economically significant, filling many community and family freezers and supplying the large pet food market. The Game Animal Council promotes adaptive management, such as Herds of Special Interest, enabling hunters to manage herds sustainably instead of eradicating them, and in the process contributing to biodiversity protection. (8) More strategic management like this would see the deer over-population problem solved and bring other positive benefits of hunting for conservation and physical and mental wellbeing.

Trout: building tourism and recreation

Trout were deliberately introduced for sport and food. Today, they are central to freshwater recreation, sustaining a multi-million-dollar tourism sector. Anglers come from across the globe for the chance to fish New Zealand rivers.

Gorse: nature’s unlikely ally

Gorse is notorious as a weed, but in regenerating landscapes it can play a surprising role. It protects native seedlings until they are strong enough to overtop it. Without gorse, many regenerating forests would struggle to establish. (9)

Ferrets and rabbits, rooks and grass grubs: using one ‘pest’ to fight another

The Queenstown trial of ferrets to suppress rabbit numbers highlights how management thinking is shifting. It challenges the idea that species can only ever be categorised as ‘bad’. Sometimes one species can be enlisted to control another. (10) Rooks were brought to NZ to help control grass grubs. Is there a connection between rooks being all but eradicated and the now over 2 billion-dollar grass grub problem? (11)

Why the ‘war on pests’ is failing

The language of eradication – ‘war on pests’ – is emotionally charged, but ultimately misleading. New Zealand’s long history of pest ‘wars’ has delivered repeated defeats, despite huge expense and effort. (12)

Despite decades of poison drops, trapping, and costly campaigns, most introduced species remain widespread. These efforts ignore the ecological niches many species now fill, and the social and cultural value they hold. They also risk alienating communities who see hunting, fishing, or fibre industries as part of their way of life and a positive way that they engage with the environment.

Our ecosystems today are not the same as those that existed 1,000 years ago. Nor will they be the same 100 years from now. The environments we live in are dynamic, novel, and constantly evolving - and introduced species are part of that story.

This reality is at the heart of the fight being led by Kate White, an artist and member of Flora and Fauna of Aotearoa from the Hawke’s Bay. She is challenging Hawke’s Bay Regional Council’s annual poisoning of rook nests – a campaign aimed at exterminating the last few rooks left in the region. Each breeding season poison is dropped into their nests to wipe them out, yet these birds are already at the edge of extinction in New Zealand.

Kate says that DRC1339, the toxin used to kill rooks, has been found to cause “severe negative welfare impacts” and it can take up to four days for some birds to die. (13)

She says that it’s costing the rate payers more than $125K a year to run the poison programme, and there’s a huge amount of conflicting evidence around whether rooks are really a problem. She and others in the region believe there’s a serious need to pause the rook eradication and look more deeply into the issue, “as the relationship between rook activity and healthy soil has not been sufficiently studied, nor has looking overseas to see how the EU, where avicides (pesticides used on birds) are banned, manages numbers”.

Her work highlights how ‘wars on pests’ can become cruel, costly, and ethically questionable, especially when targeted at species that no longer pose a meaningful threat.

Adaptive management: towards coexistence and responsibility

Many New Zealanders believe it is misguided to pour endless resources into eradication. Instead, we should focus on management, coexistence, and responsibility. This does not mean ignoring ecological challenges – far from it. It means working with reality.

A balanced approach could include:

• Adaptive management: Strategies like hunter-led management or Herds of Special Interest, which balance ecological control with recreational and cultural values.
• Designated areas and sanctuaries: Spaces where game animals, trout, or other species can flourish without conflict with conservation goals.
• Cultural recognition: Accepting that hunting, fishing, and companion animals are part of Kiwi culture, not threats to it.
• Shared responsibility: These species are here because of human decisions. They are now ours to steward.

The key is to reframe our relationship with introduced species – away from conflict, and towards coexistence. (14)

It’s time to change the conversation

Introduced species are part of the fabric of our country. To deny their presence or to treat them only as enemies is to deny reality. As Jamie Steer noted, “They are ours as well”. (15)

It is time to retire the language of war and embrace stewardship. Our ecosystems are not fragile relics to be restored to some imagined past. They are dynamic, evolving communities – and introduced species are part of them. Most importantly, we can protect our native biodiversity without the need to eradicate these species.

This is only the beginning of the conversation. Possums, deer, trout, gorse, ferrets, and rooks are just a few examples. Countless other introduced species have shaped our landscapes, economies, and identities. The task ahead is not eradication, but balance: how to live with them, manage them wisely where needed, and accept that they are now part of what makes New Zealand unique.

References:

1 ‘Jamie Steer: introduced species’: https://www.rnz.co.nz/national/programmes/saturday/audio/201816566/jamie-steer-introduced-species

2 ‘Story: Acclimatisation’: https://teara.govt.nz/en/acclimatisation

3 ‘Story: Acclimatisation’: https://teara.govt.nz/en/acclimatisation

4 ‘About fools and dreamers’: https://www.happenfilms.com/films/fools-and-dreamers

5 ‘New study finds rats and possums are big conifer seed eaters: https://www.rnz.co.nz/news/national/521628/new-study-finds-rats-and-possums-are-big-conifer-seed-eaters

6 ‘Possums and rats help stop the spread of conifers, study finds’: https://www.stuff.co.nz/environment/350331860/possums-and-rats-help-stop-spread-conifers-study-finds

7 ‘Using pests to catch pests: Ferrets enlisted in Queenstown rabbit fight’: https://www.rnz.co.nz/news/national/568629/using-pests-to-catch-pests-ferrets-enlisted-in-queenstown-rabbit-fight

8 ‘Opinion: Adaptive management must be the future for NZs wild deer’: https://nzgameanimalcouncil.org.nz/opinion-adaptive-management-must-be-the-future-for-nzs-wild-deer/

9 ‘About fools and dreamers’: https://www.happenfilms.com/films/fools-and-dreamers

10 ‘Using pests to catch pests: Ferrets enlisted in Queenstown rabbit fight’: https://www.rnz.co.nz/news/national/568629/using-pests-to-catch-pests-ferrets-enlisted-in-queenstown-rabbit-fight

11 ‘Pasture pests cost us billions’: https://www.nzherald.co.nz/the-country/news/pasture-pests-cost-us-billions/7DH6LHHMR6NPK263GNMLVRY3HY

12 ‘A war on pests and weeds is “malicious” and “incompetent” and will ultimately fail’: https://www.stuff.co.nz/science/82113675/a-war-on-pests-and-weeds-is-malicious-and-incompetent-and-will-ultimately-fail

13 ‘How humane are our pest control tools?’: https://www.mpi.govt.nz/dmsdocument/4009-How-humane-are-our-pest-control-tools

14 ‘Make love, not war: Rethinking our relationship with “invasive” species’: https://ecolitbooks.com/2025/05/29/make-love-not-war-rethinking-our-relationship-with-invasive-species/

15 ‘Jamie Steer: introduced species’: https://www.rnz.co.nz/national/programmes/saturday/audio/201816566/jamie-steer-introduced-species

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