Feral pigs--from wiki--

Feral pigs are a growing problem in the United States and also on the southern prairies in Canada.[10] As of 2013, the estimated population of 6 million[11] feral pigs causes billions of dollars in property and agricultural damage every year in the United States,[citation needed] both in wild and agricultural lands. Their ecological damage may be equally problematic with 26% lower vertebrate species richness in forest fragments they have invaded.[12] Because pigs forage by rooting for their food under the ground with their snouts and tusks, a group of feral pigs can damage acres of planted fields in just a few nights.[11] As an omnivore, it is a danger to both plants and animals endemic to the area it is invading. Game animals such as deer and turkeys, and more specifically, flora such as the Opuntia plant have been especially affected by the feral hog's aggressive competition for resources.[13] Feral pigs have been determined to be potential hosts for at least 34 pathogens that can be transmitted to livestock, wildlife, and humans.[14] For commercial pig farmers, great concern exists that some of the hogs could be a vector for swine fever to return to the U.S., which has been extinct in America since 1978. Feral pigs could also present an immediate threat to "nonbiosecure" domestic pig facilities because of their likeliness to harbor and spread pathogens, particularly the protozoan Sarcocystis.[15]

The population of feral pigs has increased from 2 million pigs ranging over 20 states in 1990, to triple that number 25 years later, ranging over 38 states with new territories expanding north into Oregon, Pennsylvania, Ohio, and New Hampshire. Some of these feral pigs have mixed with escaped Russian boars that have been introduced for hunters since the early 1990s.[16]