possumKilling possums and ferrets is a horrible job, and most of us hate it.  But it has to be done, especially if we have regenerating bush, or if our land falls within a TB control area.

We can use contractors to do the job, but we still have some choice about what method is used on our land.

Pest mammals are intelligent and sensitive creatures, so we should choose a humane method.

Inevitably, with most pest control operations there is a risk to non-target animals, so we should choose a system that minimises this risk.

Poisons

Most of the commercially available feral animal poisons appear to be relatively humane in the pest species they target.
Cyanide

  • Cyanide capsules (Feratox) are the best option of all.  Recommended!
  • They can be placed in bait stations baited specifically to attract possums.
  • They kill quickly and humanely when the animal bites into them.
  • The contractor can remove the bait stations very soon after they have been used.
  • There is no residue of cyanide left in the environment.
  • Dead animals can usually be picked up near the bait station, and this is useful if you want to collect unmarked possums for skinning.

1080

  • 1080 is biodegradable when it reaches the ground, but it has the disadvantage of persisting in the stomach of poisoned carcases, sometimes for months.
  • This means that some animals especially scavengers like dogs are at risk if they eat these carcases.
  • Licensed operators for cyanide and 1080
  • Cyanide and 1080 can be used only by licensed operators trained to make sure they are used effectively with a minimum of risk to operators, other people and non target animals.
  • The operators publicise the poisoning operation locally and put notices up around poisoned areas, so it is important for animal owners to heed these warnings.

Anticoagulants

  • Second generation anticoagulant poisons (eg Talon, Pest-Off) are readily available over the counter and are widely used to kill rabbits, rats, mice and possums.
  • But they can take weeks to kill and they can be persistent in the environment.
  • They can be found in low concentrations in many non-target animals in the wild, including native birds.
  • First generation anticoagulant poisons (e.g. NO Rats & Mice, Racumin and Rat Abate) are also readily available and are much less persistent in the environment and less likely to be found in the food chain.

Cholecalciferol

  • Cholecalciferol or vitamin D3 (NO Possums Cholecalciferol Gel Bait, Feracol) is another poison that appears to be relatively humane in possums.
  • A licence is not required to use cholecalciferol baits and they are readily available.
  • As with all the poisons there is a risk of accidental poisoning of non-target species including domestic animals so care should be taken over placement.
  • Cholecalciferol interferes with calcium metabolism and poisoned animals usually die within a few days.
  • There is little risk to scavenging animals and there is low environmental persistence with cholecalciferol as the toxin is largely broken down in the dead possums or rodents.

Cage traps

  • Cage traps can be baited with a tasty treat like apple or cinnamon to attract possums, or with meat to attract ferrets.
  • They can be set in areas frequented by the animal you're after.
  • Once set, they should be inspected frequently, at least once a day, and there's a legal requirement that they be inspected within 12 hours of sunrise the day after they've been set.
  • Any trapped pest animals can then be killed and non-pest animals (like the neighbour's cat) can be released.
  • You can help minimise fearfulness in cage-trapped animals by covering the cage with a sack until they can be dispatched.
  • Catching the possum or ferret is the easy bit - killing them humanely isn't so easy.
  • They can be killed by shooting or by trauma (blows to the head) or by gassing.

Blow to the head

  • This is not easy and not at all humane unless it's carried out by a confident, strong and skilled operator.
  • It usually takes several blows and should be followed up by throat cutting to ensure death.
  • Don't attempt this unless the animal is quiet and immobile before the first blow it.  If it isn't it could perhaps be restrained in a net.

Gassing

  • Animals in cage traps can be killed by gassing using vehicle exhaust fumes.
  • The fumes must be cool when they reach the cage and they shouldn't contain acrid fumes.
  • The cage containing the animal can be enclosed in a plastic bag, and the vehicle exhaust (from a cool engine) piped into the bag through a tube long enough to cool the gases well before they reach the cage.
  • Alternatively the gases can be bubbled through water to cool them.
  • Japanese cars with catalytic converters have reduced CO emissions but their exhaust fumes will still result in euthanasia.

Note: Gassing in this way is a safe, humane and cheap option.   It is probably more humane than any option that involves handling the animal.

Kill traps and leg hold traps

  • For possum control, if neither shooting nor cage trapping is practical then an effective kill trap such as a Timms trap could be used.
  • Unfortunately none of the kill traps has proved to be humane for ferrets.
  • The law states that leg-hold traps must not be used within 150 metres of a house without the permission of the occupier, or in any area where there is a probable risk of catching a pet animal.
  • Gin traps (the serrated edge Lanes Ace trap) have been banned.  They must not be used as they cause terrible injuries to captured limbs.
  • There are other significant restrictions on the type of leghold traps that can be used.  For example, the sale of all leg-hold traps of size 1½ or larger is now banned, with the exception of some commercially-made padded-jaw traps.
  • If leg-hold traps must be used, it is best to select types that will minimise any physical injuries, such as the padded Victor No 1 or 1½ Soft Catch traps.
  • As with cage traps, once set the traps must by law be inspected at least once a day, and within 12 hours of sunrise the day after they've been set.
  • Animals caught in traps can be killed by shooting, by blows to the head or by gassing (see above).

Acknowledgement

Our thanks to David Brittain for helping provide up-to-date information on pest poisons.

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