Integrated feral pig control
In Victoria, feral or wild populations of pigs (Sus scrofa) are declared as established pest animals under the Catchment and Land Protection Act 1994. Under the Act, all landowners have a responsibility to prevent the spread of, and as far as possible eradicate, established pest animals from their land.
Feral pigs have been present in Australia since early European settlement. Their populations were originally concentrated around settlement areas, but they have since spread across 45 per cent of the Australian mainland and are found in all states and territories. Feral pigs are one of Australia’s worst pest animal species because they not only cause extensive damage to agriculture and the environment, but they can spread diseases that threaten human, wildlife and livestock health. Therefore, it is important to manage feral pig populations wherever they occur.
Feral pig biology and behaviour
Before designing your feral pig control program, it is important to understand feral pig behaviour and ecology. The following should be considered when designing your program:
- Feral pigs eat meat and vegetable material (they are 'omnivorous').
- Feral pigs are highly intelligent and capable of adapting their behaviours to live in a wide range of habitats.
- Feral pigs may change location and behaviour according to seasonal conditions.
- Feral pigs require a reliable and adequate supply of water, food and shelter.
- Breeding can occur throughout the year.
- Sows can produce two weaned litters every 12 to 15 months, with an average of 6 piglets per litter.
- Feral pigs can travel long distances to find food or water or to escape hunting pressure.
See pig (feral or wild) for more information about their characteristics and behaviour.
Managing feral pigs on your property
- It is important to control feral pigs before they cause severe crop losses, vegetation damage, waterway sedimentation, soil erosion and livestock predation.
- Be aware that native wildlife may also be using feral pig habitat, so ensure your feral pig control program doesn't affect native wildlife.
- If any feral pig control work is to be undertaken that may result in disturbance of native vegetation, culturally significant areas or waterways, contact the responsible authorities prior to works being conducted. The responsible authorities may include local government, Agriculture Victoria, Aboriginal Affairs Victoria or the local Registered Aboriginal Party, and the local Catchment Management Authority.
- If you are planning to use traps to control feral pigs – the trap specifications, trap checking times, provision of food, water and shade, and humane destruction of trapped feral pigs must be carried out in accordance with the requirements of the Prevention of Cruelty to Animals Act 1986 (POCTA) and associated regulations. Trapping has several animal welfare implications and anyone considering trapping should read Humane Vertebrate Pest Control.
- If you are planning to use dogs for feral pig control, be mindful that there are specific requirements for the use of dogs for hunting. Under Section 28 of the Domestic Animals Act 1994, a person must not set or urge a dog to attack, bite, rush at or chase any animal except when hunting in accordance with the Prevention of Cruelty to Animals Act 1986 (POCTA).
- If you are planning to use chemicals to control feral pigs, ensure all requirements of the Agricultural and Veterinary Chemicals (Control of Use) Act 1992 and Agriculture and Veterinary Chemicals (Control of Use) Regulations 2017 are met. This includes adhering to the directions for use on the chemical label, keeping the relevant chemical use records and only using 'restricted use chemicals' if you hold the required Agricultural Chemical User Permit or other relevant permit. Chemical use record sheets and further information regarding agricultural chemical use can be found on chemicals.
Planning your program
Strategic planning can maximise the effectiveness of feral pig control while minimising damage to other animals. Consider pig density, distribution and habitat to determine what actions are most appropriate. The following steps will help in planning.
Coordinate control work with your neighbours. The best results are achieved when neighbours work together to conduct simultaneous feral pig control across a landscape, rather than just on individual properties. Remember, work on your property can be undermined by the inactivity of your neighbours, so talk to your neighbours and your local Landcare group to work out a plan for coordinated action.
Identify feral pig feeding behaviour and activity areas on your property. Map these areas for future reference. Feral pigs are often found around:
- watering points
- swampy areas
- areas with vulnerable livestock, plantations, crops and thick vegetation.
Establish a benchmark of the impact of feral pigs on your property. This will be used to measure the effectiveness of your control programs. Feral pigs can be monitored by measuring tracks, using motion sensor cameras and by measuring bait uptake at bait stations or ground rooting damage. Other signs of feral pig activity include wallows, ground rooting and mud rubs. Feral pig density can also be assessed by ground-based or aerial counts.
In addition, it is important to assess the risks to non-target animals when implementing baiting or shooting programs so they can be properly mitigated.
Use the information you have gained from monitoring to:
- target your control effort
- monitor the progress and success of your control program
- vary and improve your program.
It is important to monitor on an ongoing basis to detect and treat any re-infestations.
Use the right tools
Effective feral pig control uses all the control tools that are suitable on your property. Remember, every individual feral pig should be exposed to as many different control options as possible to ensure that those that are missed with one control option can be accounted for with another.
The following control measures may be suitable:
- property hygiene
- exclusion fencing
- harbour removal.
Consider seasonal movements of feral pigs and your ability to access areas of feral pig activity. Time your control program to manage feral pigs prior to the time of year when they cause the most damage.
Drier times when less food is available will be more suitable for baiting and trapping as alternate feed is often scarce and pigs are more likely to eat bait. Conversely, aerial shooting or ground shooting may be suitable during wetter seasons as it does not rely on bait consumption and pigs may be more active during daylight hours in cool/wet conditions. Shooting should not be done while baiting/trapping is in progress, because it can disrupt animal behaviour and reduce the effectiveness of your program.
Evaluate your success
Conduct a second round of monitoring after your control program using the same methods you used to monitor prior to undertaking any control. This will help ensure that the results are comparable and that they accurately represent any damage/density declines.
- Are pigs still present?
- Are you still experiencing damage caused by feral pigs?
- Is the feral pig damage above or below acceptable thresholds?
- What is working well?
- What could be improved?
- Do you need to change your plan?
- Have you managed all the risks?
Continue monitoring on an ongoing basis. Feral pig populations will rebound quickly, so plan your feral pig control as a regular, and ongoing, component of your property management activities.
Remember, feral pig control is time-consuming and there is no quick-fix solution.
There are a range of parasites and diseases present in Australia's feral pig population but none are likely to have any significant impact on the overall population.
New biological control agents are unlikely to be released due to the potential for non-target impacts on agricultural pig production industries.
One of the most effective methods for achieving broadscale feral pig population knockdowns is through coordinated community baiting programs. These programs should also be supported by other control techniques for best results. Two toxins are registered for use on feral pigs in Victoria: sodium monofluoroacetate (1080) and sodium nitrite.
1080 (sodium monofluoroacetate) is a lethal poison registered to control:
- wild dogs
- feral pigs.
1080 is derived from a compound found in many Australian native plants. Some Australian native animals have a higher tolerance to 1080, depending on the species. Introduced species such as rabbits, foxes, wild dogs and feral pigs are highly susceptible to 1080 poisoning. As are domestic dogs, cats and livestock.
1080 pest animal bait products that are registered to control feral pigs in Victoria are available as commercially produced shelf-stable bait. Shelf-stable feral pig baits are designed to be attractive to omnivores (such as feral pigs) but are less attractive to herbivores or carnivores.
To purchase and use 1080 pest animal bait products in Victoria you must either:
- have an Agricultural Chemical Users Permit (ACUP) with a 1080 endorsement
- have a Commercial Operators Licence (COL) with a vermin destroyer endorsement
- hold a valid Licence To Use Pesticides (LTUP) with an authorisation for the control of pest animals.
Non-target animals may be killed as a result of consuming 1080 bait or poisoned carcasses. Therefore, wildlife and livestock should not have access to 1080 bait during baiting programs and 1080 baiting should not be undertaken if the risk to non-target species cannot be mitigated. All baiting must also be undertaken in accordance with the product label and the Directions for the Use of 1080 and PAPP Pest Animal Bait Products in Victoria.
All uneaten and unused bait and poisoned carcasses must also be disposed of as per the Directions for the Use of 1080 and PAPP Pest Animal Bait Products in Victoria.
HOGGONE feral pig bait was recently registered for the control of feral pigs in Victoria. It contains a new vertebrate pest toxicant called sodium nitrite. Once ingested, sodium nitrite induces the formation of methaemoglobin by oxidising haemoglobin. This essentially reduces the blood's ability to carry oxygen throughout the body, causing major organs including the heart and brain to shut down, ultimately leading to death. Death typically occurs within two hours after bait ingestion. Available data shows feral pigs are particularly susceptible to sodium nitrite poisoning, but other species are also susceptible.
HOGGONE feral pig bait is the only registered feral pig bait that contains sodium nitrite and you do not need special authorisation to purchase and use it (e.g. an ACUP). However, you must adhere to the product label and undertake thorough risk assessment before any HOGGONE feral pig bait is laid. In addition, all HOGGONE feral pig bait must be delivered in a purpose-built bait hopper to prevent non-target species from accessing toxic bait material. It is also recommended that users successfully complete a course in agricultural chemical use.
Free-feeding is vitally important and it must be conducted at the beginning of your baiting program to:
- determine where feral pigs are currently active
- familiarise feral pigs with the bait product
- determine the amount of bait required
- monitor for non-target species.
Free feeding can be done with un-poisoned grain and/or commercially available shelf stable baits. However, it is important to offer a non-toxic version of the toxic bait you plan to use at least once before toxic baiting commences, to ensure they are familiar with it. Free-feed baits can be laid in cluster-bait piles or in specially constructed bait stations depending on the bait being used.
It is also important to set up excess free-feed bait stations at the beginning of a program to determine where the feral pigs are present/feeding. Once you identify where the pigs are regularly feeding, you can withdraw the inactive sites and focus on those that are active.
Due to natural wariness, feral pigs may sometimes fail to take baits or may take quite some time to commence feeding. Should feral pigs fail to take bait or be reluctant to feed, try using a bait attractant or potentially postpone the baiting until conditions are better suited (i.e. when alternate feed is scarce).
Poison bait should be laid at the same location as free-feeding occurred. If using bait stations, allow some time for feral pigs to learn how to access free-feed bait inside the bait station – this is critical. Once the feral pigs are familiar with the bait stations, replace the free-feed with the poisoned baits.
Bait stations are useful because they reduce the potential to harm to non-target animals and help protect the bait from the weather elements.
Exclusion fencing is a non-lethal way of protecting high-value areas from feral pigs, though it is expensive and impractical at a large scale.
In addition, very few fences will guarantee protection from feral pigs especially if they are already habituated to feeding in the area you wish to protect. Fences also need regular maintenance as they become ineffective once a breakthrough occurs.
Electrified strands can be added as outriggers or staked in front and will greatly improve the effectiveness and longevity of the fence. Also, consider wire spacings in relation to the size of the feral pigs to be excluded.
It is best to have fences built by experienced or professional fencers.
While shooting is probably the most target-specific and humane form of feral pig control, hunting alone will not achieve long-term population reductions. Shooting is also likely to quickly educate pigs making them wary and difficult to sight during monitoring activities.
Ground shooting is highly labour intensive and often opportunistic and uncoordinated. As a result, ground shooting is unlikely to reduce the feral pig population enough to reduce their overall impacts. However, ground shooting may be useful where small isolated populations of feral pigs exist or as follow up to other forms of control.
Non-toxic bait may be used by hunters to attract feral pigs to an area where they can then be shot. This approach can be useful for isolated small populations particularly when coupled with the use of a motion sensing camera and a thermal rifle scope. The camera can help determine when the pigs are active, and the thermal scope helps prevent your detection.
Aerial shooting from a helicopter is suitable for controlling feral pigs over large areas and where there is a high feral pig population density. It is highly target-specific, humane and cost effective where the terrain is suitable to detect feral pigs and where shooting is carried out by an appropriately trained and skilled operator.
Aerial shooting is not cost effective when populations are low due to the difficulty in finding widely distributed animals, nor is it suitable for areas with closed tree canopies.
The use of firearms to control feral pigs must conform to relevant firearm legislation and be integrated with other control methods.
Trapping is an effective method for managing feral pigs where poisoning is not feasible/suitable.
There are a range of trap designs including silo, panel or box traps, which basically consist of an anchored steel mesh enclosure with a lure or bait that the target feral pigs find attractive. Pigs typically gain access through a one-way entrance and are then unable to escape. Remote trigger gates are also being used more regularly. They allow the trapper to drop the gate when the feral pigs entre the trap using a remote trigger device and a real-time remote camera.
To comply with animal welfare legislation, traps must be checked regularly to minimise the time that trapped feral pigs or non-target species are held. Trapped feral pigs must be quickly and humanely destroyed.
Trapping success is affected by season, food availability and trap placement in the landscape. Free-feeding is required to familiarise feral pigs with a trap and coax greater numbers of feral pigs into the trap before it is set.
Hunting activity in the area will make trapping less effective. Trapping requires considerable time and cost for construction and ongoing maintenance of traps. Some feral pigs may become 'trap shy' and prove difficult to capture requiring alternative control methods.
Any trapping of feral pigs must be carried out in accordance with the requirements of the Prevention of Cruelty to Animals Act 1986 (POCTA) and associated regulations.
Trapping has several animal welfare implications and anyone considering trapping should read Humane Vertebrate Pest Control.
Animal carcasses should be buried or burnt to prevent feral pigs feeding on them. Presence of carcasses may attract feral pigs onto your property.
In areas affected by feral pigs, small lambing paddocks should be used to allow easier monitoring of the flock and reduce the chances of young lambs or kids being left unattended a long way from their mothers. Lambing paddocks situated close to the house are also easier to check frequently.
Other management techniques
Changes in farming production systems may be considered as a last resort where the impacts of feral pigs are extremely difficult to control.
Figures 1–6 courtesy of Jason Wishart
Figure 7 courtesy of Jager Pro