Killing pest animals is a necessary element of covenant management. Veterinarian and covenantor Marjorie Orr outlines the most humane options of pest control available to us.
Whether an animal is a pet or a stray or feral, it can feel hunger, pain and fear. Even though many feral animal species are classed as pests, we have an obligation to treat them humanely.
Pest animals have to be killed, and it's something most of us feel uncomfortable about. We have to control the numbers of rats and mice, possums, rabbits, ferrets and stoats in our environment, but they are all sentient mammals worthy of respect.
There are various methods of killing pest mammals, of course. The pros and cons of each have to be considered, and cost and convenience are usually prime considerations. We should also choose a method that causes the animals as little suffering as possible, and which keeps the risks to other animals and to the environment to a minimum.
Shooting by a skilled hunter may be one of the best options. For those who don't shoot, cage traps may be effective and humane. The cages should be inspected frequently, at least once daily, and any trapped animal shot or killed by one quick and effective blow to the head. It's not easy to do this, and it's very important to get training from an experienced trapper to ensure your technique is effective and humane.
Another killing method for animals in cage traps is gassing using car exhaust fumes. The cage is enclosed in a plastic bag, and car exhaust fumes are piped into the bag through a tube which is long enough to cool the gases before they reach the cage. This method is certainly safer for the handler and possibly less stressful for the animals than any other option which involves handling the animal.
If shooting or use of cage traps are not practical options, then an effective kill trap such as a Timms trap should be used. If leg-hold traps must be used, then select types that will minimise any physical injuries, such as the Victor Soft Catch traps. Traps such as the Lanes Ace gin trap should not be used because they frequently cause excessive injuries to captured limbs and there are alternatives which are significantly more humane.
Most of the commercially available feral animal poisons appear to be relatively humane in the pest species they target. The most commonly used, 1080 and cyanide, can only be used by licensed operators trained to make sure they are used effectively with a minimum of risk to operators, members of the public and non-target species. The operators publicise the poisoning operation locally and it is important for animal owners to heed these warnings.
Dog owners should take particular care when 1080 poison has been used. There is no antidote and it causes every appearance of extreme distress in dogs. Poisoned carcasses can remain poisonous to scavenging dogs for many weeks and even for months if the carcasses have been preserved in very dry conditions.
Anticoagulant poisons are readily available and are widely used to kill rodents. These poisons can also kill dogs which eat bait or poisoned carcasses. It is important to take sensible precautions when using rodent poisons to prevent other species from getting access to them. Fortunately there is an effective antidote to anticoagulant poison, although treatment is expensive and prolonged. Animals poisoned accidentally should be taken to a veterinarian as soon as possible after the bait has been eaten.
If a dog eats poison or poisoned carcasses, it must be made to vomit immediately. If it can't be taken to a vet immediately, it can be made to vomit by making it swallow a concentrated household salt solution or by pushing a crystal of washing soda (sodium carbonate) down its throat. It is important not to use caustic soda (sodium hydroxide).
Another important point for farmers to remember is that farm cats regularly contribute to the growing feral cat problem through uncontrolled breeding. To help minimise the number of feral cats, all domestic and semi-domestic cats should be neutered, even if they are farm cats.
Open SpaceTM Magazine No. 50, December 2000 © QEII National Trust