Australia suffers from the attentions of many invasive species, but few introduced animals pose as much of a threat to Australia's native ecology and wildlife than the humble pig. The feral pigs of Australia are intelligent, hardy and incredibly numerous -- recent estimates suggest that Australia now harbours over 24 million feral pigs. If you live in a pig-infested area, you can easily wake up to find your garden destroyed overnight by curious pigs rummaging for food.

Homeowners have the right to kill feral pigs that encroach on their land, and many large landowners may lay down traps or cages to catch these pests. However, a wounded boar is a dangerous creature indeed, and there are more humane (and less dangerous) ways to keep pigs out of a garden.

Hide your food

Removing sources of food and water is generally the best way to keep any pest out of your garden, but pigs are tenacious and notoriously unfussy feeders, so removing all sources of food may be difficult. It goes without saying that you should keep your garden free of garbage and food waste, including pet food, but you should also pay attention to the plants you grow in your garden. A vegetable garden is a big juicy target to any pig, but they also like to feed on bulb-bearing flowers such as tulips or daffodils, digging through your flowerbeds to find the nutritious bulbs.

When it comes to water supplies, there's not much you can do to keep a pig out of an ornamental fountain or waterfall. However, fish ponds and swimming pools can be secured with wire mesh or heavy-duty covers (ordinary pool covers won't withstand a determined pig for long). If you find that keeping all sources of food and water out of your garden is impractical, you may prefer to choose the next option:

Fencing

Once again, what works for other pests does not work against pigs - an adult boar is capable of digging swiftly, jumping remarkably high, and simply barging through flimsy barriers, so your fences will need to be sturdy, tall, and buried several feet deep if you want them to keep out pigs for good. 

Installing fences of this size and strength can be expensive, particularly when it comes to larger gardens, so you may find it cheaper to install a smaller, electrified fence. Electrified fences provide an added level of deterrent by giving a painful but harmless jolt to any pig that touches them. Bear in mind that an electrified fence will still need to be at least three feet high to stop pigs merely leaping over it, and that the electrified mesh should be fairly dense to stop smaller pigs slipping through it. You should also consult your local authorities before installing an electrified fence, as local planning permission or health and safety laws may prevent you from legally owning electrified fencing.

Non-physical deterrents

You have a number of options here, but they are by no means equally effective:

• Motion activated lights and alarms can be very effective deterrents initially, but eventually pigs will learn their locations and how to avoid them. Choose portable, solar powered variants if you can, and switch up their locations fairly frequently to keep the pigs on their toes.
• Many chemical deterrents are sold on the open market, but pigs will generally ignore them. A more effective (if pungent) solution is spreading crocodile dung around the perimeters of your garden - crocodiles are one of the few native creatures capable of taking down an adult male boar, and pigs will steer clear of wherever they smell them. 
• Attaching motion sensors to your ordinary sprinkler system can be a quick and easy stop-gap solution, but bear in mind that once the pigs lose their fear of your sprinklers they will become a handy water source for them.

For more information or professional help, contact a local pest control service.