By Timothy Townshend.
This first paragraph is largely introducing the lineage that Brushtail Possums inhabit, if that does not interest you skip it.
Brushtail Possums are a member of the the clade Diprotodontia, a ~25 Million Year old group ranging in diversity from the extinct Hippo-sized Diprotodont to the Tasmanian pygmy possum —the worlds smallest possum— which ranges from 6.6 to 7.5 centimeters in head-body length and weigh just 7 to 10 grams, roughly the size and weight of our Endemic Green Gecko. This clade is highly diverse and has been very successful in Australasia and contains many of the most famous animals native to Australia the Kangaroos, Koalas, Wombats etc. Brushtail Possums are specifically a member of the family Phalangeridae which are typically nocturnal, arboreal “possum-like” herbivores living in dense vegetation. Brushtails are unique in their family as they are also opportunistic omnivores so as well as competing with natives indirectly over resources in plant life… will eat native birds, their eggs, snails and many invertebrates. They can breed at any time in the year, they are highly adaptive to many environments and capable of breeding rapidly.
Much of communicating from academic levels to the general population is messy and it is often best to have clear concise messages, as a result Possums have been caricatured as gross, vermin like animals and not even deserving of moral consideration, but instead to be treated simply as a sickness to be cleaned away. No one is really blameworthy for this but it is the state of many peoples implicit views of Possums here in NZ. I wish to rid the thought from those who are willing to read this. Possums are intelligent and display the ability to learn from observing their peers 1, (though it is illegal and I would strongly advise against it) I have also heard from people in NZ who own them as pets that they are much like cats and grow quite attached to their owners. There is no reason to have more sympathy for a cat over a possum, both cause similar harm yet we consider one as cute and consider it horrible when it is killed and have near to no sympathy for the other.
I hope now that you view Possums morally worthy of consideration I will introduce to you the arguments against the killing of possums and then how we ought to respond. The arguments summarized: We arbitrarily value our natives over the lives of Possums, we create a false picture of some harmonious whole that co-operates and works together and Possums are some intruder that fundamentally co-operates with no one and destroys everything.
- Viewing ecosystems in this co-operative mode is equally as arbitrary as viewing it in terms of self interest, the fruit tree does not grow fruit so that the seed disperser may enjoy its pith it grows fruit because so that the seed disperser may eat it and poop out its seeds and it happens to be the case that the fruit tree with the more satiating or alluring fruit often reproduces more thereby creating fruit that’s pith is rather enjoyable. There is no reason to view the bee and the flower it pollinates as friends or simply self interested we have no access to the qualia of their existence all we can posit is the mechanism behind the behaviour and hope to remove as much additional baggage as we can.
- We may value our natives as symbols of the past of our country, there is enormous value in animals that have lived in regions for millions of years as they give deep insight into the ecologic past of that region. But this is not grounds for killing thousands of animals, biological ecology is an interesting field but furthering its understanding does not warrant killing possums, killing the present to preserve the past is illogical. Many of our concerns here are also just aesthetic. Much of our valuations are based on protecting human industry (farming, tourism etc.)
- The myth of a potentially destroyed ecosystem – the ecosystem we recognize today may be destroyed if Possums and similar pests were left to their own devices, perhaps not beyond recognition but substantially, the uniqueness of NZs ecology would certainly be diminished but ecosystems do not just suddenly die, the ecosystem would shift many natives would go extinct but a new semi ‘stable’ order would inevitably be established.
Now that I feel I have painted Possums in a more favourable light then most conceived hitherto, I will illustrate my desire for the future.
Firstly, I think it can be agreed in principle that all people ought to do what is in their power to rectify obvious wrongs in the world. So that though none of us personally introduced Possums to this country in the 1850s we ought to do what we can —if it can be agreed that Possums being here is an obvious wrong— to rectify it. Given this acceptance of responsibility to a problem we admittedly had no part in like that of a nonslave owner during the time of slavery has a responsibility within their power. One important point to be made clear on the onset is that inaction is not an option… Not that it isn’t a viable option but it simply is not in the wheelhouse of options we can take. If say slavery can be viewed to be an obvious wrong, standing idly by and taking no action is tantamount to participation. If Possums existence in this country can be viewed as an obvious wrong therefore our action is required.
So in what sense is their presence an obvious wrong? I will start with a cumulative case as that is likely the most effective approach then I will move on to a strict moral principle which I think ought apply.
Tuberculosis – Possums are the main TB reservoir in the country, reducing their numbers will benefit all animals infectable by bovine TB – including possums themselves. Reducing their numbers would certainly not eliminate TB but it would reduce its substantially. This may indicate some model where you simply maintain low Possum population across the country but not outright exterminate them, this is regrettably virtually impossible as possums are resilient, breed quickly and can travel up to 10km to get food or mates so they will just relocate to a better spot. Making it impossible to realistically monitor and control populations across regions, not to mention expensive.
Damage to Industry and Tourism – Damages Farming and tourism as NZ tourism massively benefits from our biodiversity pretty birds etc
Biological Ecology and the Aesthetic Argument – the importance and aesthetic value of our natives does most definitely matter, looking at a native animal can reveal treasure troves of information about their prehistoric environment. The uniqueness and beauty of our birds cannot be undersold.
In conclusion I hope to state a moral rule that we can agree on that justifies the killing of Possums without considering them in an unfair light, as they often are: When faced with a forced choice where inaction guarantees catastrophic harm to the many —that we are responsible for creating, and no non‑lethal alternatives exist, it is required to kill the few — regardless of species. Assuming relatively comparable value between each individual member of the few and the many.
