Bait consumption and the efficacy of 1080-treated grain, were determined for feral pigs (Sus scrofa) during the dry season of the Fitzroy River region of north-western Australia. There were an estimated 250 pigs on the study site (15000-ha paddock with beef cattle) before poison baiting, and group size and the basic biology of these pigs were similar to that found elsewhere in Australia. All animals at the study site were naïve to the test bait. Fermented wheat with added blood and bone was an attractant for feral pigs but added fish oil was not. Wheat and malted barley were the ‘preferred’ baits. Lupins and pig pellets were consumed in lesser amounts, suggesting that they are less/not acceptable to some feral pigs. Consequently, the efficacy of some 1080-treated wheat and malted barley was determined (n=3 sites per treatment). Three independent measures of pig activity/abundance were used. The daily sighting index before and after poison-baiting suggested that pig numbers were decreased by at least 81?100% (mean 89%) regardless of which bait was used. The take of both 1080-bait and non-toxic fermented wheat added to each station generally ceased within 1?3 days, and little take occurred during the post-poisoning follow-up. Pig tracks decreased to zero within 1?3 days of poisoning on the two sites where track plots were established. However, due to the arrival of ?immigrant? pigs ~6 days after poisoning on two sites, and the need to close down a third site before poison-baiting could be completed, we believe the absolute efficacy was greater than the 89% overall reduction. Even though they had access to bait, there was no bait-take by non-target species, either native (toxic and non-toxic bait) or domestic (non-toxic bait). The 61 pig carcases found after poisoning were within 20?610 m of active bait stations (mean 232 m), and most were found in clustered groups. These findings are discussed with respect to the development of management strategies for reducing the impacts of feral pigs, and in terms of their potential implications for developing wildlife disease (exotic and endemic) contingency plans.
|Author||Laurie E. Twigg, Tim Lowe, Gary Martin and Michael Everett|
|Secondary title||Wildlife Research|
|Department||Vertebrate Pest Research Section|
|Control method||1080 (sodium monofluoroacetate)|