<P> One common story about the feral pig population on Flinders Island is that pigs were released when the ship City of Foo Chow went ashore on the northeast coast of the island in March 1877 . On Flinders Island, feral pigs usually invade agricultural areas adjacent to the national park and east - coast swamps . Farmers consider damage caused by the pigs to be minor, as it is restricted to rooting in pasture adjacent to scrub - land edges . The total pasture area damaged each year is estimated to be less than 50 hectares . Feral pigs are reported to visit paddocks where ewes are lambing, but no lambs being killed have been reported . However, pigs being omnivores, they scavenge any carcasses left near the scrub - land . In the Strzelecki National Park on the island, the ecosystem has been severely damaged; extensive rooting in the gullies led to water erosion and loss of regenerating forest plants . Bracken fern (Pteridium esculentum) flourishes in this damaged environment and dominates large areas forming dense stands to about 4 m which prevent light reaching the forest floor . </P> <P> As of 1987, feral pigs are considered to be the most important mammalian pest of Australian agriculture . </P> <P> The practice of introducing domestic pigs into the New World persisted throughout the exploration periods of the 16th and 17th centuries . The Eurasian wild boar (S. s . scrofa), which originally ranged from Great Britain to European Russia, may have also been introduced . By the 19th century, their numbers were sufficient in some areas such as the Southern United States to become a common game animal . </P> <P> Feral pigs are a growing problem on the southern prairies in Canada and in the United States . As of 2013, the estimated population of six million feral pigs causes billions of dollars in property damage every year in the United States, both in wild and agricultural lands . Because pigs forage by rooting for their food under the ground with their snouts and tusks, a sounder (group) of feral pigs can damage acres of planted fields in just a few nights . Because of the feral pig's omnivorous nature, 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 . Feral pigs have been determined to be potential hosts for at least 34 pathogens that can be transmitted to livestock, wildlife, and humans . 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 . </P>

When were feral pigs introduced to the us
find me the text answering this question