Decisions made by men more than a century and a half ago led to me facing an unpleasant ethical dilemma a few days ago.
That is, should I subject animals to an untimely but rapid death, or a prolonged and (I can only imagine) painful one? The animal I am talking about is the Australian brushtail possum (Trichosurus vulpecula), introduced to New Zealand in 1837 for the fur trade. And it was a decision I was confronted with when I approached the regional council to have bait stations installed on our land, which borders a gully of beautiful regenerating forest.
Until now, as a town-dweller, this was not a decision I had been faced with before. It was the choice between two poisons: cyanide or brodifacoum. Once ingested the cynanide causes almost instantaneous death – the possum drops dead under the tree. In the case of brodifacoum, the possum’s blood thins, and it can take up to 3 weeks for it to die. Possums generally make their way back to their burrows, and the bodies are not found. On land where there are homes or people (and dogs) nearby, the latter is the poison recommended, because the chance of secondary poisoning is very slim. But it is not nice to think that this animal, which has ended up as a pest because it was introduced into an environment into which it did not fit, will suffer as a consequence.
It occurred to me that what links me and the men that made that fateful decision in 1837 is that we are both ‘playing god’ – making decisions that will alter nature and affect living creatures. In their case their actions had repercussions over a huge scale (both time and space), in my case, the scale is small (though combined with the efforts of neighbouring landowners, could make a significant difference to the health of biodiversity in this area)… though neither my motivation nor the scale of my efforts will be of any comfort to the possums.Photo top: a bait station on the kanuka overhanging the cliff. Above: The gully we are seeking to protect.
See also: The furry money-spinner: the history of the possum in New Zealand; And to see how much attitudes have changed in a relatively short time: The lady and the possum
envirohistory NZ 
Well said. Of course, the slow killing chemical protects other animals and birds. It may not be painful for the possum. What did you end up choosing?
Can you not, like, hunt them-castrate-release?
Sounds like you could make a program for vet school students (supplementary income).