Assessment of Spilled Toxic Bait by Wild Pigs and Potential Risk to Non-target Species.

Abstract

In 2018, a sodium nitrite-based toxic bait for invasive wild pigs (hereafter; wild pigs; Sus scrofa), was evaluated to determine its effectiveness in reducing local wild pig populations in Texas. Localized population reductions of >70% were achieved, but spillage of bait outside wild pig-specific feeders (hereafter: bait stations) caused by feeding wild pigs resulted in the deaths of non-target animals. To evaluate risks to non-target animals, we tested whether bait presentation influenced the total amount of bait spilled by wild pigs and estimated associated risk to non-target species. We found that bait spilled outside of bait stations could be reduced by >90% when compacted in trays, as opposed to being manually crumbled into pieces. We documented a mean spill rate of 0.913 g of bait per-wild pig. Conservative risk assessments for nine non-target species for which SN toxicity data exist indicate that there is relatively low risk of lethal exposure, apart from zebra finches (Taeniopygia guttata) and white mice. Our results indicate that there may be enough spilled bait per-feeding wild pig to kill 9.5 or 3.5 individuals of these species, respectively. Other species assessed range from 0.002 to 0.406 potential mortalities per-wild pig. We demonstrated that the amount of bait spilled by wild pigs during feeding and associated risk to non-target animals can be minimized by presenting the bait compacted in trays within bait stations. We recommend that baits be tightly compacted and secured into bait stations to minimize risks to non-target animals from spilled bait by wild pigs. This article is protected by copyright. All rights reserved.