Super-pig crossbreeds of wild boars and domestic pigs which have wreaked havoc on Canada’s environment now are threatening to invade the northern United States, writes The Guardian on Monday. Unlike other wild pigs the new species, which can weigh in at 661 pounds, can survive frigid Canadian winters due to their size. And the swine don’t just threaten to bring their voracious appetite for native plants and animals, but disease as well — which experts say could one day pass from hog to human, according to National Geographic. Researchers in Canada also say the super swine are “highly intelligent.” “They’re highly elusive, and also when there’s any pressure on them, especially if people start hunting them, they become almost completely nocturnal, and they become very elusive – hiding in heavy forest cover, and they disappear into wetlands and they can be very hard to locate,” Ryan Brook, head of the University of Saskatchewan’s wild pig research project, told The Guardian.