Jean Lafitte National Park’s Barataria Preserve, south of New Orleans, faces serious challenges. Rising seas may drown the preserve in the next century. Canals dredged for shipping and oil exploration channel saltwater into the preserve’s freshwater marsh, destroying the plants that maintain it.
“We have a robust but threatened ecosystem that does not need another perturbation,” says Dusty Pate, natural resources manager for the preserve—but a large, grunting, voracious perturbation is what the park has got.
Feral pigs have spread rapidly through the preserve since Hurricane Katrina. They are amazingly destructive, park officials and scientists say. Controlling them, says biologist Craig Hood of Loyola University in New Orleans, is “the most important natural resource issue at Baratara Preserve.”
Hood surveyed all the mammals in Barataria Preserve in 2005, right before Katrina hit. His camera traps recorded no feral pigs, and he saw no tracks or scat either. But they were known to be present a few miles east, and after Katrina they started to be sighted in the park as well. It may be a coincidence, but it’s also possible, Hood says, that the storm’s floodwaters washed pigs over the highway that borders the eastern edge of the preserve.
Last year Hood re-surveyed the preserve, deploying camera traps in the same places he had earlier. This time he recorded lots of pigs, mostly at night, and mostly in the forest—but also in marshes. “We have pigs in all the major habitats of the park,” says Pate. “They are everywhere.”
The infestation here is part of a national plague. Established populations of feral pigs have now been recorded in 38 states. Their numbers have exploded since the 1990s, in part because hunters have sometimes released them intentionally or have allowed them to escape from hunting preserves. They’re present now in every Louisiana parish, says Mike Kaller of Louisana State University.
They are omnivorous, smart, and energetic feeders. “Its not just browsing, it’s tearing up the soil, and compacting the soil—these are 300-pound hogs,” says Hood. They’ll dig holes a couple of feet deep to get at the roots or nuts they’re looking for. The bottomland hardwood forest at Barataria Preserve is perfect habitat for them, because the soil is rich with acorns and pecans from trees planted by farmers into the last century.
Lately the pigs have also taken to digging up palmettos—the fan-shaped spiky plants, several feet high, that are common in the understory here. They strip the roots and eat the heart.
But pigs also feed on the eggs of ground-nesting birds, reptiles, and amphibians—including alligators—and maybe on some of the smaller animals themselves. Billy Finney, a biological technician with the Park Service’s Gulf Coast Network in Lafayette, is studying reptiles and amphibians in Barataria Preserve by deploying coverboards—3-foot by 4-foots sheets of plywood and corrugated tin. The boards serve as shelters that collect snakes, frogs, and lizards, making them easier to study. “The pigs have now discovered that they can move my coverboards and prey on whatever is underneath them,” Finney says.
In a Texas park, he goes on, he once found the cadavers of four tortoises within a hundred yards of one another. Their heads and front limbs had been ripped off. Finney doesn’t have proof—but he suspects feral pigs.
Pate worries especially that pigs are spreading into the preserve’s freshwater marshes along the tree-covered levees that border the oil and shipping canals. “I’ve been in areas of marsh where pigs have torn up multiple acres,” says Pate. By eating entire plants, the pigs destroy the root structure that holds the fragile marsh together, thereby contributing to land loss—in much the same way as do nutria, the invasive rodents that the park has lost hope of eliminating. The patches of destruction left by either animal are called eat-outs.
In 2010, Finney and a partner shot 53 pigs in six months inside Barataria Preserve, hiding in stands with 12-gauge shotguns and night-vision scopes and waiting for the animals to come to feeding stations. But a female pig can have two litters a year of half a dozen piglets each. The population has exploded again. Pate says the park is planning to take up arms again soon—only this time, they may need airboats or even helicopters to hunt down the spreading menace.