Diane Peters in Undark:
There are as many as 9 million feral swine across the U.S., their populations having expanded from about 17 states to 38 over the last three decades. Canada doesn’t have comparable data, but Ryan Brook, a University of Saskatchewan biologist who researches wild pigs, predicts that they will occupy 386,000 square miles across the country by the end of 2020, and they’re currently expanding at about 35,000 square miles a year.
“I’ve heard it referred to as a feral swine bomb,” says Dale Nolte, manager of the National Feral Swine Damage Management Program at the United States Department of Agriculture. “They multiply so rapidly. To go from a thousand to two thousand, it’s not a big deal. But if you’ve got a million, it doesn’t take long to get to 4 [million], then 8 million.”