Globally, wild or feral pigs Sus scrofa are a widespread and important pest. Mitigation of their impacts requires a sound understanding of those impacts and the benefits and limitations of different management approaches. Here, we review published and unpublished studies to provide a synopsis of contemporary understanding of wild pig impacts and management in Australia, and to identify important shortcomings. Wild pigs can have important impacts on biodiversity values, ecosystem functioning and agricultural production. However, many of these impacts remain poorly described, and therefore, difficult to manage effectively. Many impacts are highly variable, and innovative experimental and analytical approaches may be necessary to elucidate them. Most contemporary management programmes use lethal techniques to attempt to reduce pig densities, but it is often unclear how effective they are at reducing damage. We conclude that greater integration of experimental approaches into wild pig management programmes is necessary to improve our understanding of wild pig impacts, and our ability to manage those impacts effectively and efficiently.

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This study assessed the proportion of a feral pig population that consumed aerially distributed baits incorporating a non-toxic biomarker (iophenoxic acid). Baits were distributed at a rate of 18 baits km-2 over 70 km2 of a seasonally inaccessible habitat. A total of 102 feral pigs were then captured by trapping and ground-shooting. Blood samples from 63 adult feral pigs were analysed for the presence of the biomarker; 40 (63%) were considered to have consumed at least one bait. Ground-shooting and trapping over 6 days resulted in 18% and 16% population reduction respectively.

The Wet Tropics bioregion of north Queensland has been identified as an area of global significance. The worldheritage-listed rainforests have been invaded by feral pigs (Sus scrofa) that are perceived to cause substantial environmental damage. A community perception exists of an annual altitudinal migration of the feral-pig population. The present study describes the movements of 29 feral pigs in relation to altitudinal migration (highland, transitional and lowland areas). Feral pigs were sedentary and stayed within their home range throughout a 4-year study period. No altitudinal migration was detected; pigs moved no more than a mean distance of 1.0 km from the centre of their calculated home ranges. There was no significant difference between the mean (AE95% confidence interval) aggregate home ranges for males (8.7 AE 4.3 km 2 , n = 15) and females (7.2 AE 1.8 km 2 , n = 14). No difference in home range was detected among the three altitudinal areas: 7.2 AE 2.4 km 2 for highland, 6.2 AE 3.9 km 2 for transitional and 9.9 AE 5.3 km 2 for lowland areas. The aggregate mean home range for all pigs in the present study was 8.0 AE 2.4 km 2 . The study also assessed the influence seasons had on the home range of eight feral pigs on the rainforest boundary; home ranges did not significantly vary in size between the tropical wet and dry seasons, although the mean home range in the dry season (7.7 AE 6.9 km 2 ) was more than twice the home range in the wet season (2.9 AE 0.8 km 2 ). Heavier pigs tended to have larger home ranges. The results of the present study suggest that feral pigs are sedentary throughout the year so broad-scale control techniques need to be applied over sufficient areas to encompass individual home ranges. Control strategies need a coordinated approach if a long-term reduction in the pig population is to be achieved. * potential migration of pigs between lowland and highland habitat areas in response to seasonal influences, and * seasonal home-range patterns.

The association of ground-digging activity of feral pigs with a range of environmental variables was examined in the wet tropics World Heritage Area of north Queensland. Approximately 4% of the surveyed ground was disturbed by digging activity of feral pigs. Significant differences in diggings were detected between highland and lowland areas and between habitat types. Diggings were more prevalent in lowland areas and coastal swamp habitats. Diggings were positively associated with roads, tracks and moist drainage lines.