Domestic pigs grown for food are selected for the slaughterhouse after 5 months and therefore have a short life cycle. Feral hogs, however, typically live four to five years, with some lasting up to eight years.
Pregnancy in sows lasts 115 days and results in an average of 12 piglets per litter. For the first three to four weeks, piglets live off milk then transition to solid food. On farms, piglets are shipped to market after reaching the target weight and size.
Domestic pigs are fed grains and soybean meal supplemented with vitamins and nutrients, though the exact recipe varies by farm. However, while feral hogs feed on roots, acorns and plant matter, they have also been known to kill birds, small animals and eat eggs. They emerge at night to look for food and travel in groups known as sounders.
Domestic pigs and feral hogs are visibly different from one another. Feral pigs are descended from their domestic counterparts but exhibit longer bristles and shorter hair, and some boars have a cartilage shield over their shoulders. However, domestic pigs that escape can become feral and start growing hair and tusks as well. Boars grow 5-inch tusks that they use to defend themselves.
In general pigs can breed very quickly with up to two or three litters per year. While not all piglets survive, their numbers increase rapidly enough for feral hogs to be classified as an invasive species.