The animals are so destructive that they cost the United States billions every year, but actually doing something about it isn’t so simple.
Early one winter morning in 2020, Kurt VerCauteren discovered a cluster of dead birds in a barren field in northwest Texas. They were small birds, mostly dark-eyed juncos, but also a smattering of white-crowned sparrows.
VerCauteren’s team had poisoned them, inadvertently. 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. The birds likely died within minutes of eating.
“I couldn’t even see the crumbs,” says VerCauteren, a wildlife biologist at the U.S. Department of Agriculture in Fort Collins, Colorado, who has spent years developing and testing pig poisons. 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. 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. When the pigs ate, they’d left tainted crumbs behind—not many, but enough.