Dr Michael Morris Animal welfare writer nzchas.canterbury

In most cases, conservationists and animal advocates are very much on the same page, both being opposed to the mindset of increased production at all costs, with its disastrous consequences for animals and the environment.

However, environmentalists and animal advocates have disagreed over a recently published Parliamentary Commissioner for the Environment (PCE) report, which recommended continued and indeed increased use of the controversial toxin 1080 for the control of introduced mammals preying on native birds and forests.

On the face of it, the PCE report makes a compelling case for the continuation of 1080.

The toxin has limited effect on non-target species, is broken down relatively easily and can be used in inaccessible areas.

It is also effective against stoats, which are arguably even more destructive of native wildlife than possums, because they prey directly on eggs and young birds.

Unlike other toxins, 1080 can kill stoats through ‘secondary poisoning', when they eat rats that have themselves been poisoned.

It is true that using 1080 it is not a particularly humane way of killing, but it is far better than anti-coagulants like brodifacoum.

Hunting, trapping and shooting are also not always humane, and they cannot be used as effectively in isolated areas.

Cyanide is a more humane poison, and if it is encapsulated and placed in possum baits, non-target poisoning can be reduced. However, it is not possible to control stoats using cyanide because it breaks down too quickly for secondary poisoning to take effect.

If we accept our present way of thinking about conservation then there appears little alternative to the continued use of 1080 in inaccessible and ecologically sensitive areas, but its use in other places can still be challenged.

Possums for example are hated with a passion, not because they destroy birds or native forests, though that is used as an excuse, but because they spread bovine tuberculosis.

The environmentally damaging effect of possums has been known about at least since the 1950s, yet Caroline King in her book on New Zealand mammals describes how funding for their eradication did not step up until the ‘70s, when their threat to our milk industry became more widely known.

So most of our supposed environmental zeal is economic self interest. According to the Ministry for the Environment State of the Environment report for 2007, most possum control is carried out, not by the Department of Conservation in native forests, but by the Animal Health Board in farmland.

Bovine tuberculosis can be adequately addressed using movement control or by keeping animals in healthy and less crowded conditions.

These options are more expensive than wholesale slaughter of possums, but this just shows where priorities really lie, and it is not with conservation.

In accessible, yet ecologically sensitive regions, alternative control methods are also available. The most obvious, and one touched on in the PCE report, is some form of contraceptive bait.

Other alternatives such as a pepper spray developed by Victoria University of Wellington, and designed to be applied to particularly vulnerable and valuable plants, could also be trialled.

Even if we accept current conservation policy, lethal control using 1080 can be restricted to inaccessible areas.

But it is by no means a foregone conclusion that the present mindset of preserving islands of national parks and other reserves in a sea of intensively farmed pasture, is the best for conservation. Environmental zealots who cry ‘the only good possum is a dead possum' while continuing to consume animal products, need to take a good look at the effects of their own lifestyle.

Meat and dairy products are indisputably enemies to conservation, leading to increased greenhouse gas emissions, water pollution and habitat destruction.

These effects cause far more damage than any introduced predator, and this effect was ironically brought to the attention of the New Zealand public through another PCE report, this time in 2004. If the numbers of farmed animals were curtailed drastically then more land could be left to regenerate into forest.

Although this would probably mean that possums and stoats would expand their population to fill this extra land, it is well known that conservation depends on the presence of large, continuous areas of suitable habitat, especially for species with larger territories such as the kiwi.

New Zealand is a biodiversity hotspot, and the expansion of available habitat will do more for conservation than demonising introduced species that did not ask to come here.

I remember a field trip to the south Coromandel ranges to study canopy browsing by possums. Looking up, I could see a few native trees with obvious browsing damage.

But then I looked over the Hauraki plains and the endless acres of monoculture dotted with sheep and cattle that would once have been lowland kahikatea forest.

This contrast between the two habitats made me realise just who has been responsible for the wholesale destruction of the New Zealand environment – and it is not a marsupial or mustelid.