The term ‘feral animals’ is generally used to describe exotic animals which have established themselves in the wild. Exotic animals are those introduced to Australia from overseas and may also include Australian wildlife which has been moved outside of its natural range. Most feral animals are either exotic animals that came here accidentally, domestic animals that have gone wild or exotic animals that were introduced into the wild for pest control or for recreational use. Most invertebrate feral animals were introduced as stowaways in transport containers or in imported crops and produce.
The Wet Topics Management Authority has produced a brochure which highlights the importance of biosecurity and management of invasive pests in the Wet Tropics. The brochure also stresses the need for education, research and community participation to help control a range of weeds, feral animals and diseases in the Wet Tropics. This includes collaboration between government agencies, local governments, landholders and industry groups.You can download a copy of the brochure below:
The impacts of feral animals on the Wet Tropics environment may include predation on native species, competition for food and habitat, degradation of habitat, soil erosion, disease and weed transmission, and changes in fire regimes. Feral animals such as pigs and dogs can also be pests for primary producers and World Heritage neighbours. A cooperative and committed approach to management between protected area managers, local government and private landholders is required for any controls to be effective. The Wet Tropics Conservation Strategy provided a list of some feral animals currently threatening World Heritage values, or with potential for damaging impacts. This list was based largely on feral animal research done by Deborah Harrison and Brad Congdon in 2002:
Many feral animals such as pigs and cane toads are widespread and have already established high population numbers within and around the World Heritage Area. Complete eradication of such established feral animals is impractical as current technology and resources are inadequate. Biological control options are being pursued for the cost effective eradication or control of established feral animals such as pigs and cane toads. Until such controls are developed, management is focused on reducing localised populations in areas where feral animals have a significant impact on biodiversity or farm productivity.
For example, feral pigs can cause extensive damage to native vegetation and crops and feral dogs can kill farm animals (see established feral animals). There are a number of feral animals in the Wet Tropics which are not currently a major problem but have the potential to spread throughout the Wet Tropics (see new invaders). Rabbits, foxes, goats and deer threaten open forest systems especially. Fish species, such as the tilapia, guppy and gambusia have huge potential to dominate aquatic systems. Invertebrate species such as the crazy ant, fire ant, European bee, fruit fly, palm leaf beetle and spiralling white fly have also been recognised as a potential threat to World Heritage integrity. For instance, crazy ants have already devastated rainforests on Christmas Island and two outbreaks have occurred around Cairns in recent years.
A number of methods and techniques are currently available for the control of feral animals, including fencing, trapping, shooting and poisoning. The type of control method chosen depends on the target species and the environmental surrounds. The effect of control techniques on non-target native species is an important consideration.