Paradox of the pig: feral status and control in the Wet Tropics

May 2001

Few environmental issues within the Economic and social impacts health is of growing concern. Japanese Wet Tropics World Heritage Area Horticultural crops suffer significant encephalitis is a potentially fatal generate the level of contention as does economic damage from pig activity. human disease spread by mosquitoes the feral pig (Sus scrofa). In the past, This impact is compounded by tension and pigs. In this case, the pigs amplify control and management strategies between landholders and authorities the disease and increase the likelihood for these animals have been as varied, over the management of the Wet of transmission to humans. Other numerous and disconnected as the Tropics Area. Those farmers who livestock diseases such as Foot-and- agencies, individuals, industries and consider the feral pig a complete pest, Mouth could become endemic if they communities who are directly or can no longer hunt these animals arrive and establish in the feral pig indirectly affected by them. once they enter World Heritage land, herd. Such an event would have and they now view this land as a safe crippling consequences for the meat Issues surrounding feral pigs range breeding ground for the pigs. export industry in Australia. from environmental, economic and social impacts through to health, Not everyone wants pigs dead medical, veterinary and cultural con- These impacts notwithstanding, the cerns. Potential solutions for control eradication of feral pigs would have are equally numerous, but none is adverse economic and cultural readily accepted by all stakeholders as impacts on other sectors of the wholly efficient, necessary or even as community. Pig hunting is not only a addressing what is seen by different significant recreational activity but sectors as their main priorities. The also supports individuals involved in feral pig problem is much more the wild game industry. The removal complex in this region than anywhere of such livelihoods could have a severe else in Australia. effect on the economies of some small rural communities. Environmental impacts The WTWHA contains some of the Pig hunting for human consumption most diverse, complex and ancient is also fundamental to many remote ecosystems in Australia. Pigs are Aboriginal communities on Cape certainly the most visible and signifi- York. Feral pigs provide a high- cant introduced animal species in this quality, low-cost food source to these ecosystem. Their ecological impacts people and are culturally significant in include soil disturbance, preying upon the maintenance of traditional forms The feral pig (Sus scrofa) and competing with native animals of wildlife harvesting and interactions and plants, and contributing to the of people with country. spread of weeds and exotic fungi. Human and animal health risks Feral pig diggings along streams and Pigs are well known as carriers of Eradication of feral pigs would cause roadsides in an otherwise naturally disease and the potential of the north economic hardship and cultural beautiful environment also create an Queensland feral pig herd to host and impacts to these communities who aesthetic impact that is not easily transmit a range of exotic diseases would understandably, oppose such a overlooked. threatening to both human and animal policy. Such concerns and interests are obvi- Striking a balance ously in direct opposition to those What is needed is an understanding described above, creating a potential of the relationship between different source of tension between government levels of reduction in pig abundance and community with regard to the and the magnitude of the economic control and management of feral pigs and environmental benefits gained. in the Wet Tropics. Clearly there is a threshold population size above which they do significant Possiblity of Eradication harm, but below which their impact Experience has shown that eradication can be tolerated and their services Pig trapped by the community based feral of pigs over wide areas is not practi- enjoyed. Understanding the level of pig trapping program; around 2000 pigs are cal, and even sustained reductions in this threshold, and evaluating the cost killed annually under this scheme. population sizes are difficult to of holding the pig population below it achieve. Feral pigs are adaptable, can can only be achieved by large-scale thrive in a range of habitats, are highly experiments in population control Further Information mobile and have a high reproductive within an adaptable management The Rainforest CRC has published the potential. Several conflicting factors framework. proceedings from a Feral Pig Work- also need to be considered: shop held in Cairns in March 1999. The • Feral pig control by conventional Certainly, given the impossible task of publication addresses the feral pig means is expensive and becomes eradicating pigs completely - we must issues in the Wet Tropics in detail. To more so as their populations learn to live with them. obtain copies contact: become sparser. Trapping pigs in Rainforest CRC Australia can cost up to $100 per PO Box 6811, Cairns QLD 4870 pig but they persist easily in in- The ecological damage of pigs tends to be highly concentrated in certain micro-habitats Phone: (07) 4042 1246 accessible areas and recover like the fringes of swamps and wetlands Fax: (07) 4042 1247 quickly from any reduction in (photographs: Jim Mitchell) Email: [email protected] numbers either by immigration or reproduction. • While feral pigs are known to cause economic damage to horti- cultural industries, this has not been quantified and therefore cannot be offset against the cost of control. Pig damage tends to aggravate farmers during a strong market, but if the market is low and fruit dumped accordingly, the pigs provide a service in cleaning up fruit dumps which would otherwise harbour fruit flies. • Aboriginal people recognise the cultural value of pigs but they also acknowledge they can damage some native bush resources.