Data from: Interpreting and predicting the spread of invasive wild pigs

The eruption of invasive wild pigs (IWPs) Sus scrofa throughout the world
exemplifies the need to understand the influences of exotic and non-native
species expansions. In particular, the continental USA is precariously
threatened by a rapid expansion of IWPs, and a better understanding of the
rate and process of spread can inform strategies that will limit the
expansion. We developed a spatially and temporally dynamic model to
examine three decades (1982–2012) of IWP expansion, and predict the spread
of IWPs throughout the continental USA, relative to where IWPs previously
inhabited. We used the model to predict where IWPs are likely to invade
next. The average rate of northward expansion increased from 6.5 to 12.6
km per year, suggesting most counties in the continental USA could be
inhabited within the next 3–5 decades. The spread of IWPs was primarily
associated with expansion into areas with similar environmental
characteristics as their previous range, with the exception of spreading
into colder regions. We identified that climate change may assist spread
into northern regions by generating milder winters with less snow.
Otherwise, the spread of IWPs was not dependent on agriculture,
precipitation, or biodiversity at the county level. The model correctly
predicted 86% of counties that were invaded during 2012, and those
predictions indicate that large portions of the USA are in immediate
danger of invasion. Synthesis and applications. Anti-invasion efforts
should focus along the boundaries of current occupied range to stop
natural expansion, and anti-invasion policies should focus on stopping
anthropogenic transport and release of invasive wild pigs (IWPs). Our
results demonstrate the utility of a spatio-temporal examination to inform
strategies for limiting the spread of IWPs.