Feral Pigs Are Invasive, Voracious and Resilient. They’re Also Spreading

The destructive swine are expanding their range in the United States and appear to be encroaching from Canada

Rancher tends to feral hogs
A rancher tends to several small feral hogs in a pen in Texas. But in the wild, these hogs are considered invasive—and they're headed north. Photo by Rodger Mallison/Fort Worth Star-Telegram/Tribune News Service via Getty Images

How are feral pigs destructive? Let us count the ways.

They are invasive and cause millions of dollars in agricultural damage each year, rooting and trampling through a wide variety of crops. They prey on everything from rodents, to deer, to endangered loggerhead sea turtles, threatening to reduce the diversity of native species. They disrupt habitats. They damage archaeological sites. They are capable of transmitting diseases to domestic animals and humans. In November, a woman died in Texas after being attacked by feral hogs—a very rare, but not unprecedented occurrence.

Much of the country’s feral pig problem is concentrated in the South, where around half of the six million feral pigs in the United States live. But as Jim Robbins reports for the New York Times, these porcine menaces are spreading.

Part of the concern is that pigs are encroaching from Canada. This fall, Kianna Gardner of the Daily Inter Lake reported that multiple feral hog groups had been seen close to the border with Saskatchewan and Alberta, and eight pigs were spotted just above Lincoln County, Montana. State and federal officials are now monitoring the border, according to Robbins, planning to hunt the pigs from the air, with the help of high-tech equipment like night-vision goggles and thermal-imaging scopes, should they advance.

But even within the continental United States, feral pigs are expanding their range rapidly. As Mary Bates reported for PLOS Blogs in 2017, research has shown that feral pigs are moving northwards at an accelerated rate. “If this trend persists, invasive wild pigs are predicted to reach most U.S. counties in 30-50 years,” Bates explained, “but likely faster if a southward expansion from Canada continues.”

The country’s wild pigs originated from domestic stock in the 1500s, brought to North America by European settlers and explorers; Hernando de Soto, the Spanish explorer who discovered the Mississippi River, is said to have introduced pigs to the Southeastern United States. Some of these animals escaped and established feral populations. Then, in the 1900s, the Eurasian or Russian wild boar was introduced to the country for sport hunting. Today’s feral pigs “include wild boar, escaped domestic pigs, and hybrids of the two,” according to Ula Chrobak of Popular Science.

The swine have proven themselves to be formidable foes. They are, for one, remarkably fecund; females start breeding at eight months, and are capable of producing two litters of up to 12 piglets every 12 to 15 months. They eat a wide range of food sources, chomping through plants—primarily agricultural crops—and killing wildlife. Feral pigs don’t just graze on crops; they’re known as the “rototillers of nature” because they root through landscapes, overturning farms, forests and fields. And while the animals thrive in the warmer climates of the south, they can survive in cold environments as well, burrowing into the snow to make “pigloos.”

While the swine get by just fine on their own, humans appear to be facilitating their spread. For one, as Bates of PLOS Blogs reports, mild winters caused by climate change may make it easier for the pigs to find food as they move north. Hunting feral pigs is a popular sport in some parts of the United States, but that also encourages people to move the animals around. The pigs, understandably, become wary when they are hunted, which can encourage the animals to scatter and establish new family groups in different locations, according to Robbins of the Times.

In an effort to curb the estimated $1.5 billion in damages that feral swine inflict each year, the U.S. Department of Agriculture recently announced $75 million in funding for a pilot program to eradicate and control feral pigs. Much of the funds will go to soil and water conservation districts, which will assist in trapping and shooting initiatives, Chrobak of Popular Science reports. But the battle against the pigs is not likely to be easy.

Dale Nolte, program manager for the U.S. Department of Agriculture’s National Feral Swine Program, tells Gardner of the Daily Inter Lake, “Multiple people say that if we were to design an invasive species that would do the most widespread damage, feral swine aren’t too far off from being the perfect specimen.”

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