Feral pigs Part II – Marauding hogs putting farmers to the sword

Feral pigs compete with livestock for pasture and access to water.

Pigs boast a huge assortment of references in popular culture, popping up in all guises from good to bad in film, fiction, expressions, music, children’s tales and even art.

Frequently the pigs are portrayed as cute, lovable animals such as cartoon icon Peppa Pig and the central character, the would-be sheep herder, in the film Babe. Even Miss Piggy, the self-obsessed diva puppet of Muppet Show fame, usually earns a smile of approval from viewers.

In real life, pigs can be looked on as endearing, pottering around in their comical manner. If a farmers’ market featuring livestock comes to town, the pigs, young and old, can be relied on to steal the show in the eyes of observers. But with the decent comes the deplorable. And taking the lead role as villains are the feral pigs of Australia. There are simply no redeeming features about these miscreants.

Feral pigs (Sus scrofa) are a serious environmental and agricultural headache. They inflict damage to the surroundings through wallowing, scavenging and digging for food. The menace of these hogs is prevalent everywhere as they are found in all states and territories, particularly around wetlands and river systems. It is estimated that there are up to 24 million feral pigs on the loose across 45 per cent of Australia. This was a figure delivered by a spokesperson for the Australian Government Department of Agriculture. The statement added that the range of estimates for feral pig populations can vary greatly due to the difficulty in surveying numbers in the wild, as well as the occurrence of wide fluctuations in population abundance and distribution in response to availability of food and water along with environmental conditions. Feral pigs are most widespread in Queensland and New South Wales and generally localised throughout other states and territories. Secluded populations can also be found on a few offshore islands.

They wreck crops and pasture, as well as habitat for native plants and animals. They spread environmental weeds. Feral pigs are hosts for pathogens such as brucellosis and leptospirosis, and could also carry diseases such as foot-and-mouth disease, African swine fever and rabies, should those viruses be accidentally introduced into Australia.

The dreaded porkers are omnivorous, busy eaters with diets consisting of just about anything. Their array of grub is endless and can include small mammals, birds, reptiles, frogs, crayfish, eggs, earthworms and other invertebrates, and all parts of plants including the fruit, seeds, roots, tubers, bulbs and foliage. They will also forage on the carcasses of dead animals that they come across.

The marauders are quite capable of levelling a vegetable harvest, while they can also smash up fruit trees (such as bananas). The gluttonous appetites of feral pigs allied with large home ranges cause all kinds of problems throughout the agricultural zones of Australia.

Farmers in particularly are left to rue the effects of these scoundrels. The pigs compete with livestock for pasture and access to water. They cause losses of an estimated 20,000 tonnes of sugarcane each year. In some areas, they kill and eat up to 40 per cent of newborn lambs. Feral pigs are estimated to cost the Australian agricultural industry more than over $100 million each year. This shocking figure was verified by the Department of Agriculture.

By tumbling and splashing plus rooting around the edges of watercourses and swamps, the accursed critters trample and destroy the vegetation that prevents erosion and provides food and nesting sites for native wildlife. And they can foul up water sources. They vie with localised animals for food and pose threats to ground-nesting birds. Feral pigs have destroyed breeding sites and degraded key habitats of the endangered white-bellied frog, orange-bellied frog and corroboree frog.

Due to a high reproductive rate and a lack of natural predators, feral pigs are quick to spread their grip.

Domestic pigs were brought to Australia at the time of European settlement as a food source, and were transported around the country by travellers. Initially, any pigs that escaped or were free to wander stayed close to human locales. However, genuine feral offshoots eventually became established. Their expansion — mainly along watercourses and floodplains — became so rapid that by the 1880s, they were deemed as pests in various regions of New South Wales. There are many species of the renegade groups including wild boar-pig hybrids.

Because they need to drink daily in hot weather, feral pigs are not found in the dry inland. In hot weather, they normally gravitate within two kilometres of water. Densities vary depending on conditions, with about one feral pig per square kilometre in eucalypt woodland, forest and grazing land, and as many as 10 to 20 per sq km in wetlands and seasonally submerged floodplains. Feral pigs are active from late afternoon to early morning. Adult male feral pigs (boars) generally roam alone over a stretch of up to 43 sq km, while females (sows) wander across tracts smaller than 20 sq km. During dry spells, mobs of up to 100 pigs may congregate around water-holes.

To breed, a male will link up with a group of 12-15 females. Feral pigs can breed from the age of seven to 12 months, and as standard would produce one or two litters of about six piglets each year. Many piglets are lost to attacks by dingoes and wild dogs, starvation and failure to maintain acquaintance with their mother. This burgeoning reproductive rate can bolster their ranks by up to 86 per cent annually in ideal conditions.

Farmers, communities and governments invest time and valuable resources combating the problems caused by feral pigs, and undertaking control to prevent spoilage to assets. The pigs continue to be a challenge and rainfall across any regions usually causes populations to increase.

However, by bringing updated information together on feral pigs, the respective interests can work collaboratively to curb numbers and manage the difficulties caused by these ever-present swine.

With this in mind, the most effective strategy would seem to be to merge various control methods (including shooting, poisoning, trapping and fencing) with suitable land management practices. In other words, it may be necessary to go the whole hog.

A large boar fleeing across the floodplain in the NT.
Pig damage on floodplains.
A group of young pigs head for the safety of the scrub.
Pigs are alert and bolt from the sound of vehicles.

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