Feral hogs are a big, expensive problem. The prolific procreators are responsible for $1.5 billion in damages and prevention each year —$800 million in damages to agriculture alone from destroying land and rooting up crops,according to the U.S. Department of Agriculture.
But trapping them is no easy matter.
Wildlife management biologist Mark McClain says it requires long hours and a lot of labor-intensive work to catch a couple pigs and, ultimately, put them down.
“Some of them escaped from hunting farms,” McClain said. “Some of them were illegally released for sport hunting. Some of them were just turned loose, domestic swine that people don’t want anymore.”
This summer, he and a couple other biologists from the Missouri Department of Conservation tried to train a sounder — the technical name for a herd of wild hogs —to come to a spot in the Mingo National Wildlife Refuge in southern Missouri. Their trap was a muddy hole full of corn. But after a week, still no hogs.
A few days later, though, McClain trapped some hogs in a corral near the tiny Ozarks town of Piedmont, Mo.
McClain said small successes like this are about controlling the pigs, not eradicating them. Because while some states successfully wiped out feral swine by jumping on the problem right away in the 1980s and ‘90s, Missouri and some other states delayed and are now dealing with entrenched populations.
Feral hogs can root up a grazing or hay pasture in two or three nights and they can disrupt feedlots.
“They eat pretty much anything and everything. They scavenge dead animals. They root for grubs and worms. They eat roots of grasses, trees. They eat any roots at all,” McClain said.
The rooting action is what makes them so destructive to ecosystems and to farmers because they can plow through a field, devouring roots of soybeans or other crops.
That’s exactly what happened to Michael Tipton last summer on his farm near Caruthersville, a small Mississippi River town deep in Missouri’s bootheel.
“Somebody came in and released a bunch of domestic hogs and then obviously turned feral on us after that,” said Tipton, who identified them as domestic because they had places where their ear tags had been cut out.
The hogs reproduced and got into about six acres of soybeans, causing about $3,500 dollars in damage.
“It looks like the ground has just been turned upside down. Big mounds that are eight or 10 inches tall and can be dug down about that deep,” Tipton said. “It’s just torn up. It looks terrible.”
He hunted and trapped some of the pigs, and the Department of Conservation shot some of them from a helicopter. By this summer, only three were left.
Missouri’s feral hogs are in pockets like that throughout the southern third portion of the state.
“Any dead hog in Missouri is a good hog,” said Rex Martensen, a field program supervisor with the Missouri Department of Conservation. The state has a shoot-on-sight policy for feral hogs, as long as it’s not firearms season for deer or turkey.
The department strongly discourages hunters from specifically going after pigs.
“The problem with promoting hunting as a good thing is that it stimulates more hunting, which stimulates the desire to have hogs in the state, and it kind of perpetuates the species and the population,” Martensen said.
Pigs reproduce quickly. A sow has two litters per year, and each litter averages six surviving piglets. About 70 percent of the population needs to be destroyed each year to keep the population in check.
Eating feral hogs is discouraged because they host diseases like brucellosis - which can be transferred to humans - and pseudo-rabies, which cannot. These two diseases can be passed to domestic pigs, according to Joseph Corn, a biologist with the Southeastern Cooperative Wildlife Disease Study at the University of Georgia.
Corn said that although these diseases have been eradicated from domestic swine, the possibility exists of reintroductions. That threat is certainly a concern in Iowa, the top pork producing state in the country. Iowa, though, is one of the success stories, along with Nebraska.
Kevin Baskins, a spokesman for the Iowa Department of Natural Resource, said small pockets appeared in the southwestern portion of that state about a decade ago.
They had fewer than a hundred pigs, so his agency took what he calls a patient-yet-aggressive approach. They trapped as many of the invasive species as they could in a single setting, instead of killing them off one-by-one.
“We got into it as early as we possibly could and were very effective in getting the few that were out there before they could get established in the wild,” Baskins said.
Within a couple years, the hogs were gone.
This story originally aired as part of Under the Microscope, a weekly program about science, health, and technology in mid-Missouri.