Its abundance reaches such levels that it can remove food from the water that other species need. The invasion of exotic plants has become a major threat to biological diversity in every area of the nation. By the mid twentieth century, this exotic had expanded its range over all of North America. It has been a successful competitor of small native birds. They are the most prolific large wild mammals in the United States and occur from Texas to Florida, in the Carolinas, in some areas of California, on eight of the major Hawaiian Islands, and on Puerto Rico and the Virgin Islands.
Hogs eat anything from grain to carrion.
Rooting for subterranean vegetation damages crops, pastures, and forest vegetation and causes erosion. Predation and habitat destruction harm native wildlife and livestock. Feral hogs are reported from 13 National Park System units. For example, rooting by feral hogs has been particularly destructive of fragile plant communities in Great Smoky Mountains National Park and at one time caused significant soil erosion and damage to endangered plant species on Santa Rosa Island in Channel Islands National Park. The distinction between changes in resources by natural processes and changes of resources by human actions has been important in the management of National Park System units.