Hunters in Richland County were abuzz recently upon hearing about federal plans to poison wild pigs that are chewing up the countryside from California to the Carolinas.
Under development by the U.S. Department of Agriculture, so-called “nasty salt” is being tested in Alabama and Texas. If the poison meets federal guidelines, it could be available for use in South Carolina within three years, the agency says.
But while the poison could be an effective weapon in the nation’s war on feral hogs, concerns are surfacing about threats it may pose to native animals that share the landscape with nuisance swine.
Wild pigs already threaten native wildlife, but putting out hog poison could make things worse if the government isn’t careful, some hunters and state wildlife officials say. The poison can be lethal to other animals, such as bears, raccoons and wild turkeys, as well as to hogs.
Chip Salak, who heads the Midlands Quality Deer Management Association, said he has plenty of questions after attending a meeting two weeks ago in which the USDA spoke about the hog poison.
“There was a lot of interest in something that would be effective” in killing hogs, he said. “It sounds potent and good, but how safe can it be?”
The poison, sodium nitrite, kills pigs within hours after they eat large concentrations of it, federal researchers say. Swine become lethargic, lie down and die, usually after falling into a coma. By reducing oxygen being carried in blood to tissues, sodium nitrite kills in a way similar to carbon monoxide poisoning. The USDA says hogs don’t feel pain, making it a humane way to eliminate them.
Kurt VerCauteren, a government scientist who is working to perfect the pig poison, said sodium nitrite is commonly used as a meat preservative and is not toxic to people or wildlife in limited amounts. But when eaten by pigs in large quantities, it is lethal. He said the poison can be used safely.
“This is essentially a big overdose,” VerCauteren said. “Nasty salt is exactly what it is.”
The key question is whether other animals can be kept away from sodium nitrite feeders that are intended to attract hogs.
“If it sounds too good to be true, sometimes it is,” said Ben Gregg, director of the S.C. Wildlife Federation. “I’m all for getting rid of as many hogs as possible, but you need to be careful.”
In Texas, concerns rose this year about the use of warfarin – a blood thinner used originally as a rat poison – to kill pigs. Critics say it caused cruel deaths and was a threat to other wildlife.
Charles Ruth, big game coordinator for the S.C. Department of Natural Resources, said his agency would be interested in using sodium nitrite to kill pigs, but only if the USDA can show that other animals won’t be affected.
“There are still a ways to go with this,” Ruth said.
Guns and hogs
Resolving the hog problem in South Carolina is important to protect other animals and plants that lure visitors to the outdoors, many agree. South Carolina’s outdoor recreation industry is estimated to have a $2.7 billion impact on the state’s economy, according to the Department of Natural Resources.
Wild pigs, the descendants of domestic animals that either escaped or were released, have become a problem in more than three dozen states, mostly across the southern half of the country, research shows. All told, the nation’s 6 million feral hogs cause nearly $200 million in crop damage every year, the agriculture department says.
Because hogs root for food and will eat almost anything, the damage they can cause to the landscape is significant. Many people liken the mess hogs leave to that of a tractor plowing through a field. Row crops, sensitive wetlands and the floor of many forests have been chewed up by hogs as the voracious porkers look for their next meals. Wild pigs also eat acorns that popular game animals feed on and they have been known to devour rare sea turtle eggs.
In addition to those concerns, swine carry diseases that can threaten livestock and people. About one-third of 119 hogs trapped at Congaree National Park from 2006-2010 carried pseudorabies and brucellosis, the latter of which can be transmitted to humans and cause what’s known as undulant fever.
Hogs are such a nuisance across the country that federal and state officials often encourage landowners to kill as many of the wild animals as they can. At the same time, the USDA has active programs to hunt, trap and shoot pigs. Among those is a program to gun down pigs from helicopters as the swine scurry through open marshes and fields.
But to make a dent in the population, the government or private landowners must kill 70 percent of the hogs in an area each year, according to the agriculture department.
And that isn’t always possible using guns and knives.
In South Carolina, hunters kill about 30,000 wild hogs annually, but more than 150,000 feral pigs still live in the Palmetto State, according to the S.C. Department of Natural Resources.
Poison would allow state and federal officials to kill more pigs, according to the agriculture department’s wildlife services division.
Last month, the U.S. Environmental Protection Agency approved more testing on how pigs react to exposure to sodium nitrite. The USDA has authorization to track feral hogs that have been exposed to bait in Texas and Alabama. If the agency receives final approval, estimated in the next three years, sodium nitrite would be available for use by federal and state wildlife managers on public or private land, VerCauteren said.
VerCauteren said research shows that the poison could work with few impacts on other wildlife or the environment.
Most notably, the material hasn’t proven lethal to scavengers that have eaten poisoned hogs, VerCauteren said of tests the USDA has conducted.
The USDA says the poison mostly affects internal organs and does not show up in meat in amounts that would be dangerous to scavengers. It also breaks down quickly after the animal dies, the agency says. Coyotes that were fed meat from poisoned pigs were not affected, he said.
““It is a perfect, modern-day toxicant,” VerCauteren said, noting that the material acts relatively quickly to kill hogs painlessly. In contrast, warfarin like that used in Texas can take days to kill animals, according to a 2017 story in The New York Times. That raised questions about whether it was a humane way to attack the pig problem.
A big challenge to protecting other wildlife is in making sure only pigs eat the sodium nitrite out of the feeders. Wildlife managers mix sodium nitrate with grain and peanut butter to make it appealing to hogs, which are particularly sensitive to high doses. But other animals also are attracted to the poisonous paste federal officials put inside feeder boxes.
Some feeder boxes contain lids that can be pushed up by a pig but not by raccoons and weaker animals, VerCauteren said.
Bigger animals – notably bears – are a different story. The powerful bruins are strong enough to open feeder boxes and get into the poisoned bait. In an effort to resolve that problem, the government is trying to develop a feeder box that would only open in the presence of pigs, VerCauteren said.
“We are working on that,” he said.
Resolving that concern would be welcome news to people like Steve Bennett, a retired DNR biologist who said he has seen firsthand how pigs wreck the environment.
Feral hogs eat most anything and are destructive in foraging for food. Hogs can devour entire stretches of corn fields and are adept at finding and snacking on food left out by hunters to attract deer to their land. Bennett, an expert on snakes and frogs, once saw fragile coastal wetland plowed up by hogs that he suspects also ate reptiles and amphibians that lived there.
“These pigs are destroying southeastern ecosystems so fast I wonder if some of these places will be able to recover” for generations, he said. “If I could snap my fingers and make every feral pig in the Southeast dead, I’d do it in a heartbeat.”