Feral pigs occupy a wide range of habitat types in Australia (Photos Andrew Bengsen and Troy Crittle).
Pigs arrived in Australia with the first fleet and were widespread across NSW by the 1880s.
Although feral pigs are descendants of various breeds of domestic pigs, they:
In NSW feral pigs are found in most regions west of the Great Dividing Range including the tablelands. High densities of feral pigs are found in western NSW floodplains and ephemeral wetlands as well as the northern slopes and plains.
Feral pigs are omnivores and have a monogastric digestive system. They will eat succulent green vegetation, meat, fruit, grain, bulbs and corms, and fungi. They can be fussy eaters and will often target specific food sources when they are available.
Ruminant animals, such as cattle, sheep, deer, and goats are more efficient than feral pigs at utilising grasses and other dry vegetation.
Feral pig breeding is flexible and greatly influenced by the amount and quality of feed available. Sows need a consistent high-protein food source to successfully breed and rear their offspring.
The feral pig:
When abundant high-quality feed is available, it:
When conditions are poor, pigs reduce breeding activity, conserving energy for survival instead of breeding.
When conditions are good feral pig populations can increase by up to 86% in one year.
Feral pigs usually form groups where:
Group size depends on the seasonal conditions and habitat:
Feral pigs are mostly inactive, and they generally do not make regular long-distance movement from one habitat to another.
They need regular access to water and shelter as they cannot reduce their body temperature easily. This is especially important when conditions are hot.
The home range size is:
Feral pigs will often restrict activity to the cooler parts of the day. When temperatures get hot, days may be spent in one area and nights spent feeding in another nearby area.
Very hot conditions may greatly restrict movement resulting in:
Few feral pigs survive longer than five years. Mortality can vary depending on the habitat and seasonal conditions. Starvation effects feral pigs of all ages. Malnutrition can make feral pigs more susceptible to parasites and diseases.
Most piglets born will never reach one year of age. They can die due to:
Feral pigs significantly impact agricultural production and the environment.
In agricultural production areas they:
Environmental impacts include:
Social impacts include human disease spread, damage-related stress and damage to visual amenity (e.g. rooting up the ground in national parks).
Feral pig damage around a freshwater lagoon (Photo Jim Mitchell)
Feral pigs are hosts and vectors of spread for parasites and diseases which can affect other animals and people. Including:
Feral pigs are susceptible to (or host and/or vector) several exotic diseases that may enter or are already present in Australia including:
Effective free feeding prior to baiting is essential to enable successful control.
Sodium fluoroacetate (1080)
Baiting feral pigs with 1080 is a cost efficient and effective way to control feral pigs and is particularly useful for reducing large populations.
1080 is a restricted chemical product. Private landholders can access 1080 bait products from a Local Land Services Authorised Control Officer.
Sodium nitrite (Hoggone®)
Hoggone® meSN is a commercially produced feral pig bait containing micro- encapsulated sodium nitrite as its active ingredient. Hoggone® is a Schedule 6 poison and is available through rural retailers in NSW. It is supplied as a peanut-based paste in a foil tray and must be used in conjunction with a pig-specific feeder.
Aerial shooting
Aerial shooting can be expensive over a short period of time; however, due to the rapid population reduction it can achieve, it can often be a very financially and temporally efficient control method.
Aerial shooting is most effective in reducing feral pig populations following baiting programs (where accessible) and when feral pig densities are low enough (through seasonal conditions or baiting) that 1000 hectares can be covered in 2-3 hours of aircraft time. To further reduce populations and prevent regrowth of feral pig populations, follow-up aerial shooting programs are recommended within four months.
Aerial shooting can be a valuable tool for controlling feral pigs in tall standing crops and when feed sources are plentiful and therefore baiting is less effective.
Like most control methods, it is important to have coordination and cooperation across land tenure boundaries to increase effectiveness.
In NSW, aerial shooting is undertaken by both private contractors (who hold necessary CASA and firearms endorsements) and the NSW Government. NSW Government shooters are a part of the Feral Animal Aerial Shooting Team (FAAST) which is made up of National Parks and Wildlife Service (NPWS) and LLS staff. FAAST shooting is carried out under strict controls and procedures.
Ground shooting
Ground shooting and recreational hunting is a less effective for feral pig control, especially in areas of high feral pig populations.
Shooting feral pigs from the ground is a method normally used opportunistically to follow up and maintain low numbers after a primary control program such as baiting and aerial shooting has occurred.
Ground shooting is often conducted using dogs to locate feral pigs. Hunters must ensure both the dogs and the pigs are treated in a humane manner.
Ground shooting should not be conducted prior to, or during, any other program of control, as it disrupts normal feral pig activity and may cause feral pigs to break into smaller groups and move to other areas.
Trapping of feral pigs is an effective technique to use:
Trapping is flexible, as most traps can be easily moved to where pig activity is current. Such as:
As with baiting to be effective traps must use free feeding in the trap until all the pigs in the area are entering the trap. This means that the door mechanism needs to be disarmed and pigs are free to enter and exit the trap.
Some patience is required as wary pigs or new additions to a group may take 10-14 days to enter the trap.
Traps should always be sited in a location where they can be partially shaded because of pigs’ poor ability to dissipate body heat.
Fencing is sometimes used to protect valuable enterprises in a small area. Effective pig proof fences have been designed but need to be thoroughly maintained to sustain their effectiveness.