Feral pigs are descended from introductions of European wild hogs for sporting purposes, and from escaped domestic swine that have established feral populations. European wild hogs have several distinguishing characteristics that set them apart from domestic or feral hogs. Among these are brown to blackish brown color, with grizzled guard hairs, a mane of hair running dorsally from the neck to the rump, a straight heavily tufted tail, and ears covered with hair. Characteristics of feral hogs are varied, depending upon the breed of the ancestral stock. European wild hogs and feral hogs interbreed readily, with traits of European wild hogs apparently being dominant.

These feral members of the pig family should not be confused with the collared peccary, or javelina (Tayassu tajacu), the only native pig-like animal (Family Dicotylidae) living in the wilds of North America. Collared peccaries are much smaller than feral pigs, more uniformly and thickly coated and grayish in color, with a light collar over the shoulder. Their tails are nearly absent and their upper tusks point down, rather than up. Its habits and adaptations restrict it to living in brushy deserts, rocky canyons, scrub oak forests and arid mountain foothills of southern Texas, southern Arizona and southern New Mexico. As a native animal, the javelina is a natural and accepted member of North America's native community of plants and animals. Not so for the feral pig.

Distribution
Today, feral pigs and hybrids of the Russian wild boars are found in 23 states with the possibility of yet-undiscovered populations in several more states. The largest populations are in the coastal states surrounding the Gulf of Mexico and California (not surprising, since Spanish explorers settled these territories). Feral pigs are found chiefly in western North Carolina, eastern Tennessee, West Virginia and, in California, on Santa Cruz Island and Monterey and San Luis Obispo counties. Small numbers of pigs are found in New Hampshire, Pennsylvania and Vermont, Alabama, Arizona, Arkansas, Georgia, Florida, Louisiana, Oklahoma, Oregon, South Carolina and Texas.

Behavior
Feral pigs, similar to people, can mate any time of the year. If a sow is not bred during the two or three days she is in estrus (in heat), she will become sexually receptive again 21 days later. Generally pigs mate during two peak breeding seasons: one in winter (December through February) and another in early summer. When a sow is in heat, boars gather and fight for dominance slashing their sharp tusks at a rival's shoulders. Boars travel between family groups in search of receptive sows. The dominant male mates first. The less dominant males slip in and mate after the dominant boar is finished breeding.

Sexual maturity and reproductive ability of feral pigs greatly depend upon nutrition and habitat. Under optimal conditions, sows can begin breeding at 6 months of age, and produce up to 4 litters per year with each litter consisting of 4 to 12 piglets. In northern portions of their range, biologists report that reproductively active sows generally only produce 2 litters per year consisting of 4-8 piglets.

Diet
Unlike some other hoofed animals, the feral pig has a simple stomach and does not chew cud. Feral pigs are opportunistic omnivores that eat whatever plants or animals happen their way. They especially relish acorns as well as hickory and beech nuts in the autumn. At other times of the year they eat forbs, grasses, leaves, berries and other fruits, roots and tubers, corn and other agricultural crops, insects, crayfish, frogs, salamanders, snakes, mice, eggs of ground-nesting birds, young rabbits, fawns and young livestock, such as lambs, calves, and kids. They can also kill larger livestock that are weak from illness or injury. When fresh meat is not available, feral pigs will also readily scavenge carrion.

Pigs feed most heavily at dawn and dusk, spending the majority of the day either wallowing in mud holes or resting in dense vegetation.

Habitat
Good feral hog habitat in timbered areas consists of diverse forests with some openings. The presence of a good litter layer to support soil invertebrates and/or the presence of ground vegetation affording green forage, roots, and tubers is desirable. Hogs are also fond of marsh and grass-sedge flats in coastal areas, particularly if wild grapes are common. During hot summer months, "wallows," or depressions dug in the mud by feral hogs, are much in evidence near marshes or standing water, such as along roadside ditches.