Pressures on the World Heritage Area - Feral Pigs

Feral pigs possibly arrived in Australia with traders from Asia and Papua New Guinea, as well as with European colonists, and are now well established in the Wet Tropics.

Feral pigs are the major pest animal in the Wet Tropics. They are widely distributed, damage endangered ecosystems and compete with threatened species. Their habit of wallowing and rooting around the edges of watercourses and swamps disturbs natural vegetation, spoils water quality, causes erosion, allows weeds to grow and destroys the habitat of small native animals. Pigs compete for the food of other animals such as the cassowary and bettong. They spread weeds, diseases and parasites.

Pigs also cause damage to farmlands and crops. A study undertaken to measure pig damage on selected farms estimated costs to be $4,099 per annum for banana farms and $10,632 per annum for cane farms. Feral pigs may carry foot and mouth disease and there is the potential for this disease to spread into domestic animal populations at great expense to the industry.

Feral pigs are difficult to control because they are so adaptable. Their habitat is often inaccessible to humans. They reproduce so well that repeated control programs are required to reduce the population. Their omnivorous feeding habits give them a large variety of available food sources, and their home ranges are large. Control programs need to be conducted over a large area to be effective.

Control methods

Many control methods have been attempted:

• Poison baiting is regarded as the most effective method of quickly reducing feral pig numbers. However, available baits may still be taken by other species. With new methods and technologies, baiting has the potential to be an effective method of pig control in the region.
• Trapping is becoming more effective and widely accepted. A pig specific gate trip mechanism has been developed to minimise the risk of trapping non-target native species such as cassowaries and wallabies. A pig trapping program in the Wet Tropics caught over 1500 pigs.
• Shooting and hunting with dogs have been commonly used to control pigs. While they may be effective in dry seasons when pigs are congregated at available waterholes, there are strict controls over the use of firearms and dogs in protected areas and shooting is ineffective in rainforest areas and rugged terrain.
• Fencing can be effective for small, critical areas. However, the most successful pig-proof fences are the most expensive and maintenance costs are also high.

At present all these methods are capable of lowering pig numbers in local areas for a short time. However, they have failed to substantially lower pig numbers over time across the region. Any effective biological control is considered to be 10-20 years away. Researchers are now focusing on development of effective baits for feral pigs.

The Department of Natural Resources and Mines website also includes information on feral pig management.