Interaction risk between invasive wild pigs and livestock: Implications for potential infectious disease transmission...

Invasive wild pigs (Sus scrofa) are free-ranging domestic-wild boar hybrids expanding across Canada. Their proximity to livestock farms increases wild pig-livestock interaction (WPLI) and disease transmission potential. This study quantified proximity and spatial associations between wild pig reports and livestock farms, estimated current and potential WPLI risk areas, and surveyed producers to monitor wild pig presence. We used a generalized linear model with gamma distribution to compare wild pig report locations to random locations across six livestock farm types. WPLI risk areas were estimated by overlapping relative densities of reports and farms. We developed a resource selection function to predict potential WPLI risk assuming wild pigs occupy all suitable habitat. Finally, 231 livestock producers were surveyed to document wild pig presence and interactions. Wild pig reports occurred significantly closer to livestock farms than expected by chance (2.90 km average difference), with 22% within 500 m of farms. Smallholder pig and wild boar farms showed the strongest spatial associations, while commercial operations showed minimal overlap with current wild pig distributions. We developed a resource selection function (RSF) to predict potential WPLI risk assuming wild pigs occupy all suitable habitat. RSF identified optimal wild pig habitat as fragmented agricultural landscapes with 37% grassland, 35% broadleaf forest, and 18% wetlands. Suitable habitat distribution indicates potential substantial WPLI increases for smallholder operations (70-78%) and commercial farms (51-102%). Producer surveys confirmed wild pig presence at 4% of farms, with limited correspondence between predicted risk areas and reported interactions, highlighting the importance of complementary information sources. WPLI risk is spatially heterogeneous and concentrated around specific farm types, guiding targeted monitoring, surveillance, and biosecurity interventions.