Canada’s wild pig problem may soon spread. According to a recent study published in the journal Biological Invasions, Canada’s invasive swine has a “high potential” for moving south across the border into the mostly wild pig-free states of South Dakota, North Dakota, Montana, and Minnesota.

The study is the culmination of years of research on Canada’s wild pig problem. Wild boars were brought to Great White North in the 1980s and 90s for meat and high-fence operations. Some people crossed them with domestic pigs to create hybrids that Dr. Ryan Brook, a professor at the University of Saskatchewan and co-author of the recent study, termed “super pigs,” which could survive in cold climates. In the early 2000s, the market for those pigs fell out, and many farmers released them into the wild.

“In 2010, we started to map these free-ranging wild pigs in Canada. We documented an exponential and completely out of control spread of them,” Brook tells Field & Stream. “Then, the next obvious question was: what’s likely to happen next? Where are they likely to go?”

That’s what the recent study, which was primarily funded by the U.S. Department of Agriculture, assessed. Researchers put GPS collars on 31 feral hogs and studied their movement and distribution—as well as the habitat they favored. The pigs congregated in areas with wetlands, deciduous forests, and agricultural production, primarily corn. The scientists then used this data to create maps showing the habitat connectivity of where they’re likely to spread—particularly into eastern Montana, North and South Dakota, and western Minnesota.

map showing pig habitat connectivity
The maps were developed using GPS collars and habitat selection modeling. Kramer et. al

“The U.S.-Canada border is a political boundary, not an ecological one. There’s no wall or big fences. Most of the boundary is continuous farmland or forested landscapes,” explains Brook, noting that pig populations in Manitoba are just a two- or three-day walk from the border. “Animals can easily cross it, and [wild pigs] are likely to do exactly that.”

“We went from having a general concern about pigs crossing the U.S. Canada border to having very detailed maps showing where they’re most likely to move and establish populations,” he adds. “This can be used to target control efforts.”

Brook notes that hunters and anglers should be particularly concerned about the toll of the ecological impacts that the pigs could incur. “This has very important conservation implications because wild pigs use wetlands and forests, and they do tremendous damage,” he says. “They’re rooters and tear the ground up. They are an ecological trainwreck. They eat anything from small mammals like mice to ducks and geese, all the way up to adult whitetail deer that they will kill and eat. There’s a long list of reasons why the last thing you want is invasive wild pigs.”

As part of the study, researchers captured a pregnant 638-pound sow—a testament to the serious size that some of these invasive hogs can reach. Brook also noted that the pigs are more mobile than some other wild populations, and some of the GPS-collared pigs ranged from three to four hundred square kilometers, compared to European wild hogs, which only typically range from one to four square kilometers.

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“These pigs have high reproductive rates, are very mobile, and have a high capacity to spread,” says Brook. “This study is one of the most important of my career because it highlights the massive risk of wild pigs and how far they can—and likely will—move if something different isn’t done. Canada has been failing really badly at addressing the issue. If something doesn’t change soon, we’re in serious trouble in Canada, and we’re not being good neighbors if we’re letting them run wild into the U.S. as well.