Feral hogs originated from domestic pigs that either escaped or were released. European settlers in the 1500s brought domestic pigs over for a food source. Later, Eurasian wild boars were introduced for sport hunting which increased the feral pig population containing the original domestic stock, wild boars, and a hybrid of the two. People still today have been known to release domesticated pigs for different reasons and escaped pigs further increase the feral population.
Current Distribution and Trends

Current trends show feral hog populations are rapidly growing and are widespread across the United States, approximating 6 million individual animals and causing an estimated $2.5 billion in annual damage. Feral hogs are currently found in 35 of the 50 states, including Hawaii, and all the southeastern states ranging from North Carolina south to Florida and west to parts of eastern New Mexico. They can also be found in California and some counties in Nevada, Arizona, Utah, and Oregon have reporting sightings. Feral hogs have expanded their range north as well, showing up in states like North Dakota, Oregon, and New Hampshire.
Reproduction

The growth of feral swine populations and the increased economic, environmental, and social damage they cause is due to a combination of factors, specifically their high reproductive capacity, lack of natural predators, and their ability to adapt to a variety of environmental conditions. In ideal conditions, a group of feral hogs can double their population in just 4 months. If they have a high-quality diet, females may be able to breed before 6 months of age. Feral pigs are social creatures and sows will form groups called sounders with one to several sows collaborating to watch after their collective young. Sows typically have one litter of piglets per year but have been known to have two, and they can have them at any time of the year. Litters average 3 to 8 piglets but can be up to 13 depending on the age of the sow, nutritional intake, and time of year. Boars (males) reach sexual maturity around 18 months and prefer to remain solitary outside of mating activity.

Feral pigs are very adaptable and inhabit tidal marshes to mountain ranges and everything in between. Cold temperatures are somewhat limiting, and these animals tend to stick below the snowline in mountainous areas, showing an overall preference for areas that remain mostly above freezing. However, populations are gradually expanding into the northern US and Canada, which regularly have below-freezing temperatures. When encountering high temperatures, feral hogs appear to prefer dense vegetation with proximity to water. They will feed mostly at night and seek shaded wallow areas during the heat of the day. In winter, they will feed during the warmest part of the day.

Feral swine are omnivores and will consume both plants and animals. Plants make up most of their diet, but they have been known to eat invertebrates, bird eggs, and even young calves and lambs on occasion. They are attracted to livestock pastures and production areas which tend to have high value nutritional grasses, feed, and other items of interest. Feral pigs will remain in the forest when acorn production is high (late summer and fall) and will rarely leave an area when there is a reliable food source. During winter, after acorns and other food sources have been consumed, pigs tend to wander beyond their normal range looking for food sources including farm fields, herbaceous plants, and invertebrates. Food scarcity makes winter an ideal time to trap pigs with bait, usually corn.

Feral pigs roll around (wallow), root, and dig up the ground looking for food. These activities often create erosion leading to degradation of nearby waters. Ground disturbance from foraging pigs can also destroy crops and create conditions for invasive vegetation to establish and spread. Feral pigs carry several diseases and parasites that can affect livestock, humans, and other wildlife species.