Feral pigs, also known as wild hogs or razorbacks, are descendants of domestic swine (Sus scrofa) that either escaped or were intentionally released into the wild. Introduced to North America as early as the 1500s by settlers, their numbers and range have expanded dramatically. Feral swine are now considered an invasive species, with an estimated population of over six million individuals found across more than 35 states in the U.S. Their high reproductive rate—females can produce up to two litters of four to twelve piglets every 12 to 15 months—allows populations to grow quickly, compounding the destructive impact they have on natural and human environments.
Ecological and Habitat Degradation
The foraging behavior of feral pigs inflicts extensive physical damage on natural habitats through “rooting” or “tilling.” In their search for underground food sources like roots, tubers, and invertebrates, pigs use their snouts to overturn vast expanses of soil and ground cover. This disturbance destroys native vegetation and disrupts soil structure, increasing the land’s susceptibility to erosion, particularly in sensitive riparian areas. Rooting also prevents the natural regeneration of forests by consuming seeds, nuts, and seedlings, altering the overall composition of plant communities.
Feral pigs negatively affect water resources due to their wallowing behavior, which is necessary for cooling since they lack functional sweat glands. These muddy wallows become sources of contamination as the pigs deposit sediment and feces directly into streams, ponds, and wetlands. This activity increases the water’s turbidity and elevates nutrient concentrations, harming aquatic life by covering fish spawning beds in silt and reducing dissolved oxygen levels. The pigs’ movements also damage stabilizing vegetation along stream banks, accelerating erosion and further degrading water quality.
Beyond physical destruction, feral pigs act as opportunistic predators and competitors, threatening native wildlife species. They consume the eggs and young of ground-nesting birds, reptiles, and amphibians, leading to substantial losses in vulnerable populations. They have been documented raiding the nests of marine turtles and consuming ground-dwelling fauna. Furthermore, their diet, which includes acorns and tubers, puts them in direct competition with native animals such as deer and squirrels that rely on these same food sources.
Agricultural and Economic Losses
The financial burden caused by feral pigs is the widespread destruction of agricultural production, totaling over $1.6 billion annually across certain U.S. states. Feral pigs damage crops through direct consumption, rooting up plants, and trampling, severely reducing crop yield. High-value commodities such as corn, peanuts, rice, sugarcane, and soybeans are frequently targeted, leading to millions of dollars in direct revenue loss for farmers.
Feral swine also inflict costly damage on human-made property and farm infrastructure. They routinely destroy fences, water lines, irrigation ditches, and specialized equipment like trellises and nets associated with orchards and vineyards. Additionally, their rooting and wallowing in pastures create deep ruts and uneven terrain that can damage farm machinery and make fields nearly impossible to harvest with tractors. The cost to repair or replace this damaged infrastructure reaches hundreds of millions of dollars for both crop and livestock operations.
Livestock producers face significant losses from both predation and resource competition. Feral pigs prey on young animals, including newborn lambs, goat kids, and calves. They also compete directly with domestic livestock for pasture and feed, often contaminating food and water sources with feces. The combined losses attributed to predation, veterinary costs, and disease transmission to livestock were estimated at $85 million in one recent assessment across 13 states.
Managing these invasive populations requires massive expenditures from landowners and government agencies. The effort to control feral swine through trapping, monitoring, and aerial removal translates into hundreds of millions of dollars in management costs for producers each year. In 2021, crop and livestock producers together spent over $470 million on control efforts, including expenses for labor, fencing, bait, and ammunition. These costs represent a continuous overhead for agricultural operations simply to mitigate the damage caused by this invasive species.
Disease Transmission and Public Health Concerns
Feral pigs serve as reservoirs for a range of pathogens, posing serious biological risks to commercial livestock, native wildlife, and humans. They carry numerous viral and bacterial diseases and parasites that can be transmitted to other animals and people. The threat to the commercial swine industry is particularly significant, as feral populations can harbor highly contagious diseases like Pseudorabies and Classical Swine Fever.
These diseases, which are often fatal to domestic swine, can be spread through nose-to-nose contact or by contamination of feed and water. A major concern is that feral swine could act as a vector for a Foreign Animal Disease, such as African Swine Fever. Although never established in the U.S., its introduction could devastate the country’s pork industry and halt international trade. Their ability to range widely and interact with farm animals makes them difficult to contain as a disease threat.
A number of zoonotic diseases, which can be transmitted from animals to humans, are carried by feral pigs and present public health concerns. These include Swine Brucellosis (Brucella suis), which causes flu-like symptoms in humans, and foodborne illnesses like E. coli and Trichinellosis. Transmission to humans commonly occurs through handling or butchering infected carcasses without proper protection, or by consuming meat that has not been cooked to a safe internal temperature. Contamination of surface water with fecal material is another route, potentially elevating bacteria levels in streams and irrigation canals used by people and livestock.