Many allow hog hunting, but вЂњrecreational sport hunting only takes about a quarter of the wild hog population every year,вЂќ says Jack Mayer, a researcher at the Savannah River National Laboratory in South Carolina. States have developed a spectrum of strategies to control the menace.

If thereвЂ™s a signal that it could be dangerous, theyвЂ™ll pick up on it.вЂќ But hogs вЂњare smart, theyвЂ™re risk averse, and they donвЂ™t want to die. вЂњYou want it to be effective, you want it to be humane, and you want it to only kill what you want to kill,вЂќ VerCauteren says. How do you find something that will kill a hog, and only a hog? ItвЂ™s a quest that scientists like VerCauteren will solve with not just biology and chemistry but also engineering and technology informed by game theory and risk calculation. Poisoning is a vastly complicated undertaking that requires knowledge of not only what the animals eat, but also when they eat, and where they go, and what other animals are around. What they eat, other animals like raccoons and bears also eat and when they die, other scavengers may eat them. Analyses of the hogsвЂ™ stomach contents and feces show that they eat almost anything, including tree stumps, small vertebrates, sea-turtle eggs, amphibians, baby goats, turkey eggs, turkey hens, and young deer-вЂњanything containing carbon,вЂќ VerCauteren says.Д«ut feral hogs donвЂ™t wreak havoc in a vacuum. Between destruction and control costs, the animals cost the country at least $1.5 billion annually, according to the USDA, though ongoing research indicates the actual figure is considerably higher. Wild hogs pillage cornfields, forests, and cemeteries, leaving behind messes that look like the work of angry asteroids. Read: The clock is ticking on AmericaвЂ™s вЂferal swine bombвЂ™ вЂњSometimes you have to remove the animals to solve the problem.вЂќ вЂњWhen you have a grossly overabundant species, the kind of damage they can do is huge,вЂќ VerCauteren says. The animals have become a growing scourge across the country, with as many as 6 million of them causing enormous damage to crops, livestock, and native habitats from North Carolina to California and Texas to Florida. For nearly a century, scientists have investigated chemicals that can fell big, vertebrate pests-particularly feral swine. There are currently no poisons that can be legally used in the United States against wild hogs, but not for a lack of options. But, he adds, it only takes an amount the size of вЂњa grain of rice to kill a little bird.вЂќ вЂњIt takes a handful to kill a hog,вЂќ VerCauteren says. When the pigs ate, theyвЂ™d left tainted crumbs behind-not many, but enough. In the days before, VerCauteren and his collaborators had assembled heavy, sophisticated feeders and filled them with the mash laced with a heavy dose of sodium nitrite, a salt often used in processed meats. The birds were the unintended victims of a field experiment to test a toxicant-one intended for feral pigs, but no other animals-that had been developed in Australia. Department of Agriculture in Fort Collins, Colorado, who has spent years developing and testing pig poisons. вЂњI couldnвЂ™t even see the crumbs,вЂќ says VerCauteren, a wildlife biologist at the U.S. The birds likely died within minutes of eating. The clues were clear, the death uncomplicated: The birds had flown in before dawn to scavenge deadly morsels of a contaminated peanut paste, left behind after a sounder of wild hogs had torn through the area in a feeding frenzy. VerCauterenвЂ™s team had poisoned them, inadvertently. They were small birds, mostly dark-eyed juncos, but also a smattering of white-crowned sparrows.

Early one winter morning in 2020, Kurt VerCauteren discovered a cluster of dead birds in a barren field in northwest Texas.

We were here together poison