Hugh Warwick, BBC Green Room 30 Mar 10;
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.
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.
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.
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
