Investigation of sodium nitrite as a control tool for feral pigs

摘要

Feral pigs (Sus scrofa) have expanded their distribution drastically in recent decades and have provided a formidable challenge for natural resource managers seeking to halt the spread and reduce damages caused by this invasive species. During 2013, in cooperation with the Texas Parks and Wildlife Department, Kerr Wildlife Management Area (KWMA), I investigated several factors related to the ongoing issue of feral pig populations in Texas, including: 1) palatability and efficacy of 3 sodium nitrite formulations produced by Southwest Research Institute, and 2) assessing the need for future investigations on the risk of secondary poisoning to vultures and other avian scavengers. Efficacy testing led to the decision to further investigate alternate encapsulation matrix as the best performing formulation achieved only 50% mortality. Remote camera data from the study revealed the possibility of both learned and taste aversion to the baits by feral pigs, indicating the need for a more stable and palatable encapsulate. Feral pig carcasses were monitored using remote cameras to identify scavenger species in the area which could be at risk from sodium nitrite killed pigs. Results suggest that both turkey and black vultures (Cathartes aura and Coragyps atratus) may be at risk from secondary poisoning and that additional testing on captive vultures is needed to estimate residual levels in pig tissues and digesta and vulture sensitivity to sodium nitrite. These studies will help researchers and managers better understand the complexities of developing and delivering a safe and effective toxicant to feral pigs.