Feral Pig Invasion Dynamics in Central Brazil: Human-Driven Introduction, Landscape Drivers, and Ecological Consequences

Abstract

Biological invasions by feral swine are among the most important drivers of ecological change worldwide, yet invasion dynamics remain poorly documented in tropical South America. In Brazil, the recent spread of wild boar and wild boar-domestic pig hybrids (javaporcos) overlaps with long-established populations of free-ranging feral pigs (porco-monteiro) in the Pantanal, creating a unique scenario of dual invasive lineages of Sus scrofa. We reconstructed the spatiotemporal invasion process of feral swine (S. scrofa) across the state of Mato Grosso do Sul (MS), Brazil, using historical occurrence records, captive-breeding data, landscape variables, detection frequencies, and occupancy estimates from 2007 to 2017. The invasion expanded from 29 municipalities (36.7% of the state) in 2007 to all 79 municipalities by 2017. During this period, at least 247 breeding facilities were identified across 59 municipalities, including numerous informal and clandestine operations involving wild boar and hybrids (javaporcos). Municipalities with the largest numbers of breeding facilities and reproductive stocks consistently coincided with areas of highest invasion intensity, indicating that propagule pressure from captive populations strongly influenced feral swine expansion. By 2017, invasive populations occupied approximately 3.2 million hectares (8.85% of the state territory), with the greatest occupancy concentrated in agricultural landscapes dominated by soybean, maize, sorghum, and sugarcane production. Detection frequency and occupied area were positively associated with croplands, exposed soil fields, and water-associated habitats, suggesting that agricultural mosaics linked by riparian corridors facilitate invasion and persistence. Conservative population estimates ranged from 11,850 to 47,400 individuals statewide, although carrying-capacity scenarios suggested populations could exceed 500,000 animals under favorable conditions. Detection patterns involving native peccaries (Tayassu pecari and Pecari tajacu) indicated differential coexistence responses to invasive swine, with collared peccaries apparently more sensitive to heavily invaded landscapes. Our findings demonstrate that feral swine expansion in central South America was driven by the interaction of anthropogenic propagule pressure, permissive governance, and highly suitable agricultural environments, highlighting the urgent need for coordinated monitoring, regulation of captive breeding, and large-scale adaptive control programs.