Wild pigs (Sus scrofa) are among the most widespread and destructive invasive mammals in the world. Understanding the spatial ecology of this species is foundational to effectively mitigating further range expansion. We compiled size estimates of home ranges of wild pigs from 30 locations worldwide and modeled the relationship between home-range size and both abiotic (evapotranspiration, latitude, precipitation, and temperature) and biotic (vegetation productivity and mammal species richness) environmental factors. Size of home ranges varied markedly, ranging from 0.62 to 48.3 km². Mammal species richness was positively correlated with home-range size and was the only predictor in the best model; other abiotic factors typically correlated with richness, i.e., latitude and evapotranspiration, were not significant predictors of wild pig home-range size. Despite indicating correlation rather than cause, our analyses were conducted at the scale of the home range and therefore may support the invasion paradox hypothesis for mammals, which states that biotic interactions have a greater influence on invasive species at finer spatial scales. While we do not suggest that mammal species richness can preclude populations of wild pigs from continuing to spread in their native or non-native ranges, our correlative results suggest that areas with a diverse mammal community may be more resistant to invasion. This finding supports the intrinsic value of conserving native species and highlights the need for future work exploring the specific mechanisms by which species richness and biodiversity can influence the ecology of invasive species.