Knowledgebase > Wild Pigs

Wild Pigs

Last updated 7 January 2019

People established and sustain wild populations

Pigs (Sus scrofa) were brought to Australia with early European settlers, who kept them in unrestricted and semi-feral conditions. By the 1880’s, pigs had run wild across NSW. They now occupy a wide range of habitats in the north and east of Australia, and also occur in pockets in the south west. Total population estimates vary from 13 million to 23.5 million[1].

An academic study analysing genetics[2] showed there are two processes involved in the maintenance of feral pig populations in WA: (1) gradual expansion of their range by natural dispersal, and (2) supplementation of existing populations by (presumably) hunters intentionally moving pigs to new areas. This study found evidence that illegal translocation of wild pigs has been ongoing and widespread - it isn’t limited to the present generation or to a specific cohort of pigs. The authors suggest it is reasonable to assume a similar phenomenon is occurring elsewhere in Australia.  

 

Hunting Methods

Use of Dogs

‘Pig dogging’ or ‘pigging’ refers to the hunting of wild pigs with purpose bred and specially trained dogs. At the command of human hunters, pig dogs will track, flush, bail and then ‘hold’ wild pigs. The Australian Pig Doggers and Hunters Association Inc (APDHA) recommends using up to five dogs per pig (two for bailing, two for holding and one young dog in training)[3]. They are taught to latch onto the pigs’ ears, so the hunter may approach more safely and immobilize the pig. This is done by lifting one or both hindlegs, or by flipping pigs onto their back. Once restrained, the hunter will stab the pig with a hunting knife in either the throat or side of the chest.

Targeted pigs suffer a prolonged period of distress as they are chased, harassed and mauled by a pack of dogs. Once the hunters arrive, the dogs are often encouraged to continue biting as the pigs’ final struggle is filmed. Although the APDHA national code of practice states pigs are to be dispatched with “a single knife stick to the heart”, you would be hard-pressed to find a single example of this occurring in any footage published online or in pig dogging DVDs. The vast majority of footage reveals pigs are stabbed repeatedly and bleed for minutes before losing consciousness.  

Pig dogs are trained from a young age to be tough and highly aggressive towards other animals. Many are housed in deplorable kennel conditions and may be starved before hunts to ensure they keenly locate and capture the pigs. Hunters also frequently lose track of their pig dogs in the bush, and they then become a major threat to dingo populations (hybridisation through interbreeding), farmed and native animals.

Pig hunting also presents risks for the dogs. When boars are under attack, they will typically stand their ground and attempt to drive their tusks into the attacker. This means pig dogs regularly suffer injuries, including fatal wounds, while they are in locations far from professional veterinary attention. The dogs are also at significant risk of hyperthermia, exhaustion and dehydration because of the huge physical exertion required during hunts that may last an entire night.

Finally, pig hunters present a disease risk for the broader human population since wild pigs may harbour bacteria such as Brucella suis. The greatest risk factor for the disease brucellosis is feral pig hunting, with all confirmed cases in northern Queensland between 1996 and 2009 resulting from the activity[4]. Transmission occurs during slaughter by direct contact with feral pig blood or body fluids, or by aerosol spread. In addition, pig hunters hold regular events that attract substantial crowds and involve ‘weigh in’ competitions[5]. This means potentially infected carcasses are transported long distances to the event, handled by numerous people from different towns and are held in close proximity to areas where people are eating and drinking.  

Poisoning

Wild pigs are killed with poison-laced grain, cereals, meat and pellets. The poisons used include 1080 (sodium fluoroacetate), yellow phosphorus (CSSP) and warfarin. 1080 causes severe central nervous system disturbance, convulsions and ultimately respiratory failure. Pigs, and many other animals who have ingested 1080, show symptoms of extreme distress that last from several hours to several days, making it a most painful and slow death[6]. CSSP causes severe irritations in the gastrointestinal tract and takes 2 to 4 days to kill. Warfarin is an anticoagulant that causes internal haemorrhaging and takes between 1 and 2 weeks to kill[7].

Firearms

Shooting is a commonly utilized lethal control measure for wild pigs. It may be conducted by operators on the ground or in the air. The goal is reportedly to achieve an instantaneous loss of consciousness and rapid death with a single bullet to the brain or heart. In reality, animals are live targets, which means they move unpredictably. Considering the sheer size of the Australian wilderness and the millions of points at which hunters may kill, there is no conceivable way that authorities can regulate hunting activity to ensure targeted animals are ‘dispatched’ quickly.

Bowhunting

Bowhunting is a type of archery where bows (compound, longbow or recurved) and arrows with a ‘broadhead’ are used to hunt land game animals, including pigs.

Bowhunting is a notoriously cruel pursuit; clean and quick deaths resulting from a broadhead arrow penetrating the heart or major blood vessels are rare. Most animals will be initially wounded and then die hours, days or even weeks later from haemorrhaging or infections[8].

Tasmania is the only jurisdiction where bowhunting is illegal. On mainland Australia, it is legal to bowhunt declared game or pest animals on private property (provided appropriate permission has been granted) and on specified Crown Land and State forest areas[9].

 

“Pest Control”

Impacts?

The recognized potential negative impacts of wild pigs include habitat degradation through their natural rooting and foraging behaviours, predation on and competition with native animals, reduced crop yield and lamb production due to predation, and disease transmission to humans (in particular Brucellosis and Leptospirosis).

However, a recent review[10] explains that many of the potential impacts of wild pigs in Australian ecosystems have been inferred from anecdotal information and untested retroductive hypotheses of studies or systems outside of Australia. The authors suggest the lack of experimental evidence for wild pig impacts is an indication of the difficulties in gaining reliable understanding of a species with such a high level of behavioural plasticity.

It is important to recognize there are Australians who value wild pigs as a resource and source of entertainment because these people have a vested interest in sustaining feral populations. This presents obvious complications for governments tasked with pest control or management. For example, wild pigs have been commercially harvested since 1980 with a majority of animals being exported to European countries as ‘wild boar’. In 2015, it was estimated that the market or demand for wild boar in Europe could be up to 20,000 animals each month[11].

How effective are existing methods?

Government agencies facilitate recreational hunting, claiming that each non-native animal killed assists in reducing the perceived impact of that species on the environment, other animals and agricultural productivity. However, unless hunters kill more animals than can be replaced each year, they do not reduce the population size and therefore do not reduce the alleged impacts of those species[12].  

Importantly, many so-called invasive species have the ability to quickly produce large numbers of offspring, but most do not survive because there are not enough resources to sustain them. As with every other wild animal, disease and predation also reduce the numbers of young who survive. For example, a scientific study in Kosciuszko National Park revealed just 15% of wild piglets survived their first year[13]. A hunter who kills one pig may simply be enabling the survival of another pig due to reduced competition for food and suitable territory.

 

 

References

[1] Australian Government Department of Sustainability, Environment, Water, Population and Communities 2011: https://www.environment.gov.au/system/files/resources/a897fd1d-3d5c-408d-957e-3cf03f0b103b/files/pig.pdf

[2] Spencer P, Hampton J. 2005. Illegal translocation and genetic structure of feral pigs in Western Australia. Journal of Wildlife Management, 69: 377-384.

[3] Australian Pig Doggers and Hunters Association Inc. ‘Code of Conduct’: https://www.apdha.org.au/info/code-of-conduct

[4] Eales K, Norton R & Ketheesan N. 2010. Short Report: Brucellosis in Northern Australia. The American Journal of Tropical Medicine and Hygiene, 83(4): 876-878.

[5] Paul Robinson, 04/06/2018 ‘Hundreds of feral pigs caught and killed in Australia’s largest hunting competition’, ABC Capricornia. https://www.abc.net.au/news/2018-06-04/hundreds-feral-pigs-caught-in-aust-biggest-hunting-competition/9829360

[6] Thiriet D. 2007. In the spotlight - The welfare of introduced wild animals in Australia. Environmental and Planning Law Journal, 24(6): 417-426.

[7] PestSmart states the time that it takes for pigs to die from CSSP and warfarin poisoning: https://www.pestsmart.org.au/poison-baiting-for-feral-pig-control/

[8] RSPCA Australia Knowledgebase, ‘What is the RSPCA’s view on bow hunting?’. https://kb.rspca.org.au/what-is-the-rspcas-view-on-bow-hunting_368.html

[9] Australian Bowhunters Association Inc, Frequently Asked Questions: https://bowhunters.org.au/index.php/bowhunting/bowhunting-info/trophy-bowhunters-club-of-australia/8-aba-general/59-bowhunting-frequently-asked-questions

[10] Bengsen A, Gentle M, Mitchell J, Pearson H & Saunders, G. 2014. Impacts and management of wild pigs Sus scrofa in Australia. Mammal Review, 44: 135-147.

[11] Carmen Brown, 14/04/2015 ‘Wild boar exports suffer as accredited hunter numbers drop’, ABC Rural. https://www.abc.net.au/news/rural/2015-04-14/wild-boar-market-hit-by-dropping-hunter-numbers/6383368

[12] Invasive Species Council, Fact Sheet - ‘Recreational hunting NSW: claims v facts’, https://invasives.org.au/wp-content/uploads/2014/02/fs_rechunt_NSWvfacts.pdf

[13] Saunders G. 1993. The demography of feral pigs (Sus scrofa) in Kosciusko National Park, New South Wales. Journal of Wildlife Management, 69: 377-384.

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