Page last updated at 08:33 GMT, Tuesday, 30 March 2010 09:33 UK

The curious case of the Kiwi hedgehog

Hugh Warwick
Hugh Warwick

Hugh Warwick was a vocal opponent of the cull of hedgehogs on the Scottish islands known as the Outer Hebrides. However, in this week's Green Room, he argues that sometimes there are compelling reasons to support a cull.

A hedgehog (SPL)
Wildlife management is often portrayed as a purely objective endeavour; you look at the numbers and make your decision. But wildlife management can never be objective

Killing hedgehogs is wrong, isn't it? The public outcry against the cull of hedgehogs in the Outer Hebrides was intense.

So why am I, a devoted fan who helped end the cull of Hebridean hedgehogs, finding it hard to argue against the killing of hedgehogs in New Zealand?

The reason begins back in the mid-19th Century. In retrospect, what happened seems a little foolish. No, more than that, it seems barking mad. New Zealand is still cleaning up the mess that arrived thanks to the 1861 Animal Acclimatization Act.

The Act enabled the establishment of Acclimatization Societies to help ease the pains of being so far from home. There were some pretty obvious species that were shipped over from the UK: deer, rabbits, goats, pigs and foxes, for example.

What could possibly go wrong?

As we now know, these introductions, along with accidental tourists like rats and weasels, have wreaked havoc among the ground-dwelling birds, reptiles and insects who had adapted to a life without such predatory mammals.

Squashed hogs

But there was one species that seemed to fit right in: the hedgehog. Acclimatisation was not just about species to eat and hunt. It was also about making the new residents feel more at home.

Again, what could possibly go wrong? For many years, the sight of hedgehogs squashed on the roads was little more than a curiosity. They were welcomed into gardens. And some zoologists reckoned them to be the most benign of introductions.

Yet even in their homeland, hedgehogs can cause a problem. The Uist hedgehog cull came about because of the deliberate introduction of hedgehogs to the Hebridean islands in the mid-1970s in an attempt to control garden pests.

This act of seemingly green pest-control inadvertently let loose marauding, egg-hungry mammals that emerged each spring from hibernation to a veritable smorgasbord, thanks to the bounty provided by the internationally important populations of wading birds.

The hedgehogs were killed because the conservationists at Scottish Natural Heritage (SNH) argued they would suffer "slow and lingering deaths" if translocated back to the mainland.

Weta (SPL)
The weta is apparently one of the hedgehog's preferred snacks

I was fortunate enough to undertake a study that suggested this was not true, and now SNH is working with the one-time rescuers, ensuring the hedgehogs get re-homed on the mainland.

So when the evidence of a hedgehog problem started to emerge from New Zealand, it would not be unexpected to find me siding with the vocal opposition to lethal control. Especially when reports started to emerge of a new and improved trap that was to be deployed in problem areas.

Backbreaking work

There is something a little disturbing about the effectiveness of the newly improved trap, the DoC 250. It was developed by the Department of Conservation when it was found that existing traps including the Victor Snapback and the Waddington Backcracker failed to meet the National Animal Welfare Advisory Committee requirements.

There is a move from the DoC to persuade people to stop seeing hedgehogs as cute and harmless. A report in the Manawatu Standard begins: "Next time a hedgehog snuffles and shuffles its way into your garden, think of it as a rat…" and goes to explain that a "hedgehog Swat team" is being prepared to eradicate the prickly pests from two islands in the Hauraki Gulf.

Rangitoto and Motutapu islands, just a short distance from Auckland, are being targeted for restoration. This will involve removing seven different mammalian pests, cats, rabbits, stoats, brown rats, black rats, mice and hedgehogs.

The problem with hedgehogs in New Zealand is simply that they like to eat some of the more endangered species. CCTV cameras revealed disturbing levels of anti-social behaviour on their part, eating eggs of banded dotterels, black stilts and black-fronted terns.

Young hedgehog being fed (Image: Hugh Warwick)
Once on a diet of solids, hedgehogs eat several species

One hedgehog was found with 283 weta legs in its stomach (and having seen pictures of this insect, you can only concede that this was a brave hedgehog) and scientists have found that hedgehogs also prey on native skinks.

So, what is to be done?

Wildlife management is often portrayed as a purely objective endeavour; you look at the numbers and make your decision. But wildlife management can never be objective.

There is a subjective judgement taken as to which species need to be controlled. We make value judgements about species based on where they are, what they are doing and how difficult it would be to control them.

Uist hedgehogs had the advantage that there was plenty of hedgehog-friendly habitat into which they could be released, back on the mainland. But New Zealand is a very different story. This is an alien species that is upsetting the fragile ecosystem. They could not be released. So what then? Build a hedgehog zoo?

Wildlife management can lead to dangerous sentimentality. If I had found that the Uist hedgehogs had suffered "slow and lingering deaths" on translocation, I would have supported the cull. The rights of animals not to suffer should be considered.

A solution to New Zealand's hedgehog problem may be coming from an unexpected quarter. A recent study has shown that hedgehog numbers are falling at a similar rate to the UK, despite apparently very different sets of pressures.

Perhaps New Zealand's hedgehogs will fade away, or at least become reduced to a residual population that does little harm, allowing wildlife managers to just control the most sensitive areas.

Reaching a compromise between extermination of the charismatic alien and the protection of the endangered natives must surely be a welcome target.

Hugh Warwick is a freelance writer and ecologist. His latest book is A Prickly Affair, My Life With Hedgehogs

The Green Room is a series of opinion articles on environmental topics running weekly on the BBC News website

Do you agree with Hugh Warwick? What should be done about the hedgehog problem in New Zealand? Is there always a case to oppose a cull? Can such wildlife management issues ever really be a purely objective effort for the benefit of whole ecosystems?

As stated in the article there are lots of introduced 'pest' species in New Zealand not just mammals but marsupials, insects, plants and even algae. Removing one of them will help but other will come in their place. Do we only think that Hedgehogs are cute or nice because of the way they are portraded in childrens books and TV?
Liam, Gloucester

Nothing is ever completely right, or completely wrong - the kind of childlike simplicity expressed in the opening paragraph "Killing hedgehogs is wrong, isn't it?" demonstrates why and how so many people mistake environmentalists for gormless sentimentalists - or just, mentalists. Grow up and address the issues on their own merit, not by referring to a fallacy.

Im all for the cull, as described. I dont think the animals could be moved to another location, and the only tidy way to deal with them is to shoot them individually, as poison or traps wont discriminate properly. I think a marksman needs to make a decision about each individual invader, and take responsibility for killing each one cleanly. to do the job properly, will probably take years, so they should probably make a start as soon as possible.
Tris, Ipswich

Yes hedgehogs are cute in their almost comical shuffling, bumbling way. However, as pointed out in the article - they are one of the many introduced mammal species that the local unique wildlife have no evolutionary tricks up their sleeves to deal with them. As much as the European settlers very naively thought they may be a nice touch of home (along with lots of invasive plants I might add) the current generation has an obligation to protect species that should never have met these predators by any (humane) means necessary. Tuatara, Kiwi, Weta etc are a national (and world) treasure - I defy anyone to read about some of these creatures and not be struck by their almost 'lost world' status.
David W Scott, Wellington, NZ

I think that you'll find the introduced Australian possum far out weighs the proplems of hedgehogs on the environment. I say start with the possums (but add hedgehogs to the list), and once they have effectively been eradicated (which is highly unlikely)then DoC can move on to dealing with hedgehogs.
brian, Hamilton, New Zealand

New Zealand has a unique biodiversity. Controlling any introduced pest species is essential as a parallel to the varied work DoC and hundreds of kiwi vounteers do to increase numbers of decimated populations of indigenous species. Frankly they need all the help they can get.
Genevieve Smith, Auckland, New Zealand

We also have 30 million possums destroying the tree canopy and eating endangered kiwi eggs. Plus rats, and the cats and the dogs of irresponsible owners to deal with. Not to mention stoats, weasels, wasps and other introduced pests. If you want the hedgehogs back, come and get them.
Mario McMillan, Auckland, NZ

There's a huge amount of hypocrisy surrounding these types of problems. Surely the largest and most dangerous introduction is the human being? They've caused more species to disappear than any other 'accidental tourists'. Salving your conscience by trying to stop other animals doing the same thing as you've done isn't always successful - it doesn't always work out how you expect. A lot of effort went into culling feral cats in areas of Australia and it transpired in some places they were eating mainly feral rabbits which were a bigger pest.
JD, Milton Keynes

As someone from NZ and someone who did my thesis on conservation in NZ, I have a very different view point to many people over here regarding hedgehogs. The fact is, that here they are native. They evolved here, and the ecosystem evolved with hedgehogs as a part of it. In New Zealand it is very different. They are pests. They may well live nicely in the back garden, but the problem is that a hedgehog does not know the difference between a back garden and the native bush. They cause untold damage (this article does not do justice to the problem that hedgehogs cause in NZ) to native and especially critically endangered wildlife. NZ birds, insects, reptiles and amphibians did not evolve with mammalian predators so have no defence mechanisms to deal with them. Hedgehogs are not the only problem, it extends to cats, stoats, weasels, ferrets, rats, mice, possums, deer, wild pig, introduced birds and the list goes on... The fact of the matter is that hedgehogs (along with other introduced mammals) must be eradicated from the wild. It is the fault of people, not the native wildlife that these animals have been introduced. If something is not done about it quickly then I fear that NZ will be the next Hawaii. We will be talking about those wonderful animals that used to exist.
Ben Burrows, London, UK

Beatrix Potter has so much to answer for. It is about time animal "lovers" stopped confusing themselves with ecologists and excusing their irrational unscientific behaviour/arguments. Human-caused problems need to be faced up to properly, like adults. What a disgraceful waste of resources in a world of so much suffering, to repatriate a pest species which is in no danger of extinction elsewhere. What a waste of conservation resources to do it, when budgets are miniscule and time of the essence. The job of killing the introduced populations of hedgehogs wants doing in Scotland and NZ, quickly and efficiently. Grown up decisions need no euphemisms. What about the environmental cost of repatriating from remote islands? Grow up, cull the hogs and stop whingeing about it.
Toby, Fareham

I have been on Rangitoto Island today. The silence due to lack of native birds was noticeable but understandable due to lack of food. Non-natives do need to be removed, but in an ideal world I would prefer regularly cleared traps, then euthanasia for the larger pests. Save the bullets for the human litter bugs. Think before you breed or translocate anything.
Andy, AKL, NZ

Growing up in NZ it was exciting to have a mammal as an interesting creature in the garden (I believe the only native NZ mammal is a tiny fruit bat) ... yes we fed them and encouraged them as kids - but as an adult the detrimental effect of the hedgehog is obvious (one only needs to observe the devastation caused by rabbits and possums to see where it could go). If the DOC could provide a humane and efficient method of elimination I think most people would relucantly agree with the cull ... admitting though that it is hard to ignore the 'cute' factor of the wee buggers.
Sharon, Edmonton, Canada - ex New Zealand

Killing hedgehogs is wrong??? They are apparently very good eating (although I confess to never having eaten one); as are pigeons, lambs, calves, deer, baby pigs and dogs (in the far east at least). What is this? One rule for the poor bovines, ovines, porcines and canines and another for Mrs Tiggywinkle!
Paul BJ, Luxembourg

Its a bit like culling kangaroos. they are a cute looking animal but when they reach plague proportions (20 million) due to favourable weather and climate conditions they cuase famine conditions to themselves and all other wild animals (wombats, bilbies and many other Australian marsupial animals)struggling to survive
Alexander, South Australia

Yes, I agree with your article that NZ needs to cull hedgehogs. Because of our mild winters, Hedghogs do not hibernate and so greatly proliferate to destroy the eggs of endangered birds which are native to NZ, and unique in many ways.
Marie Parker, Auckland New Zealand

Conservation in NZ is all about killing. Dogs, cats, rats, stoats, weasels, pigs, possums, thar, chamois, hedgehog, rabbits, ferrets, goats, mice, etc. etc...are decimating a country that pre-Maori settlement, had only 2 species of mammal (bats). NZ is also the second worst country after Hawaii for exotic plant introductions going wild.
Sure, ecology is not static, and in many ways NZ is fighting a losing battle - but while the bird that is our national identity- the kiwi - continues to see 95% chick mortality rates, and while we still care for the other amazing birds, insects and plants that are found nowwhere else on the plaent, then the killing will and has to continue. I for one have killed several hedgehogs while bushwalking in Auckland - as long as it's humane, I don't see a problem.
jared , london, uk (ex Auckland)

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