During the past year, federal trappers have killed more than 100 wild hogs at Congaree National Park under a program they hope will keep pigs from menacing visitors and destroying rare plants at the nationally acclaimed preserve southeast of Columbia.
South Carolina’s only national park for years has had trouble with wild pigs that managers say are damaging the 27,000-acre woodland and flood plain. But sporadic efforts to protect the park by reducing the pig population had not proven successful.
So in November 2015, the National Park Service brought in another federal agency to make it a full-time effort.
The U.S. Department of Agriculture’s wildlife services division put out traps and began slamming the doors on pigs that wandered into the agency’s enclosures. Resource officers then shot pigs in the fences. In some cases, government sharpshooters have killed pigs during special night hunts.
It has been a grim job at times, but park officials said they had to do something to curtail the number of hogs at the park. Other methods of controlling hogs, such as relocation, weren’t practical, park records show.
Studies show that pigs are causing problems by rooting up the soil, which threatens native plants and makes the ground suitable for the spread of invasive species.
“They do a lot of damage,’’ said Liz Struhar, Congaree National Park’s chief of resource management.
Struhar said the National Park Service didn’t “have a lot of capacity internally at Congaree to handle our feral hog problems. The USDA has been a big help to us. It has been huge.’’
As of this past week, federal officials had killed 112 pigs since November 2015, she said. Most of the pigs were in the range of 150 pounds, but at least one was as large as 300 pounds, according to the Department of Agriculture.
Neither Struhar nor the USDA had an estimate on how many pigs exist at Congaree National Park. But the number could easily exceed 400.
In one three-month period in 2012, hunters shot 440 wild pigs on private property adjacent to the national park, according to Congaree’s 2014 hog management plan. Many hogs that roam the park cross onto private land nearby, then return to the national park.
Whether the hog elimination program will work is unknown, since Congaree Park is in the first year of a sustained effort to kill wild pigs. Studies show that hunters would need to kill 70 percent of the pigs in an area to make any dent in the hog population over a period of years. Wild pigs are prolific breeders.
But Struhar said she’s noticing fewer signs of pigs since the agriculture department arrived one year ago with the full-time effort. Combined with a major flood in 2015, the agriculture department’s work appears to have reduced the number of hogs, she said. Struhar said the $65,000 program will continue next year and she hopes to keep it going beyond that, although that depends on funding.
The Park Service and the USDA plan to provide more details of the effort during a public meeting in St. Matthews later this month. The meeting, scheduled for Nov. 17 at Tri-County Electric Cooperative, will lay out the problems pigs are causing at Congaree National and how the park is trying to limit damage from feral swine.
Agriculture officials will also demonstrate for the public how to trap wild hogs and discuss diseases the animals carry.
Congaree National Park is an internationally acclaimed wetland area known for its tall hardwood trees and extensive flood plain. About 100,000 people visit the park annually. The park contains vast stretches of wilderness that are ideal habitat for animals and plants.
Statewide, wildlife officials say South Carolina has more than 150,000 feral pigs roaming the landscape from the coast to the mountains. Hunters kill about 30,000 of them each year, but it hasn’t been enough to tame the growing wild hog problem, the Department of Natural Resources says.
The agriculture department’s wildlife services division kills about 1,000 hogs annually for landowners and government wildlife preserves in South Carolina, said Noel Myers, state director with the USDA’s wildlife services division.
To get rid of hogs, the agency relies partly on enclosures that can be shut remotely by hog trappers. Cameras show officials when large numbers of hogs have walked in to eat corn or other bait. With a simple command from a cellphone, wildlife officers can close a door or drop a trap on the hogs.
“Technology is increasing our effectiveness and efficiency,’’ Myers said.
Federal officials then visit the closed traps, shoot the pigs and drag the carcasses into the woods away from walking trails and waterways.
Feral hogs are considered a problem in much of the country, but particularly in the South. The descendents of once domesticated swine, pigs since Colonial times have either escaped from farms or have been let go intentionally across the region by people who wanted to hunt them.
Through the years, the hogs have developed wild characteristics, sporting long hair and tusks. They are a problem for many reasons, wildlife managers say, but much of the concern focuses on landscape damage.
The animals use their snouts to dig in dirt and mud, looking for roots, nuts, worms and insects. That sometimes destroys rare native plants already living in forested or open land.
Pigs, for instance, are threatening efforts to re-establish long-leaf pine forests at Congaree National because they eat pine cones that carry seeds, which are vital to regenerating the rare forest, Struhar said. One 2008 study found that “pig disturbance was common and abundant’’ in parts of the park’s flood plain.
Rooting by hogs creates furrows, much like a tilled farm field. That allows plants to grow that are not necessarily native to the area, biologists say. Birds can spread seeds with their droppings.
Wild hogs also bring problems that threaten people. Swine can be aggressive, officials say. No visitors have run into problems with hogs yet, but Struhar said “we have had a couple of researchers who felt a little threatened by hogs.’’ Additionally, the animals carry diseases. Brucellosis, a disease fatal to livestock and many wild animals, can cause fever in people who come in contact with sick pigs.
The park’s management plan says wild swine have lived in the Congaree flood plain for 200 years, but the population increased at the national park after hunting was banned in 1982.
Nationally, at least 4 million feral hogs exist, but the number might be as high as 11 million, according to the Center for Invasive Species Prevention, which tracks the appearance of non-native species. The number of states with established wild pig populations is 40, acccording to the USDA. That’s up from 19 in the 1990s, the center says.
Biologists say pigs are growing in numbers for two key reasons: Sportsmen have increasingly released them as a species to hunt, and pigs breed quickly and successfully. A hog reaches sexual maturity at six months and can produce more than a dozen piglets each year, according to the National Park Service.