Feral pig
A feral pig is a domestic pig which has gone feral, meaning it lives in the wild. The term feral pig has also been applied to wild boars, which can interbreed with domestic pigs. They are found mostly in the Americas and Australia. Razorback and wild hog are sometimes used in the United States in reference to feral pigs or boar–pig hybrids.
Definition
A feral pig is a domestic pig that has escaped or been released into the wild, and is living more or less as a wild animal, or one that is descended from such animals. Zoologists generally exclude from the feral category animals that, although captive, were genuinely wild before they escaped. Accordingly, Eurasian wild boar, released or escaped into habitats where they are not native, such as in North America, are not generally considered feral, although they may interbreed with feral pigs.Swine may directly or indirectly serve as subjects for rewilding and pleistocene rewilding prospects, and degrees of deleteriousness of feral animals may vary among cites of introductions; accidentally reintroduced wild boars in Western Europe are also not considered feral, despite the fact that they were raised in captivity prior to their releases, and the ones in North and South America potentially replace Platygonus and other prehistoric peccaries.
North America
Continental United States
Domestic pigs were first introduced to the Americas in the 16th century. Christopher Columbus intentionally released domestic swine in the West Indies during his second voyage to provide future expeditions with a freely available food supply. Hernando de Soto is known to have introduced Eurasian domestic swine to Florida in 1539, though it is possible that Juan Ponce de León had already introduced the first pigs into mainland Florida in 1521.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, 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.
Feral pigs are a growing problem in the United States and also on the southern prairies in Canada., the estimated population of 6million feral pigs causes billions of dollars in property and agricultural damage every year in the United States, 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. 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. 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. 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.
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.
Feral pigs are opportunistic omnivores, with about 85%-90% of their diet being plant matter, and the remainder animal. Plants have difficulties regenerating from their wallowing, as North American flora did not evolve to withstand the destruction caused by rooting pigs, unlike European or Asian flora. Feral pigs in the U.S. eat small animals, mostly invertebrates like insects and worms but also vertebrates such as wild turkey poults, toads, tortoises, and the eggs of reptiles and birds. This can deprive other wildlife that normally would feed upon these important food sources.
In some case, other wildlife are out-competed by the feral pigs' higher reproductive rate; a sow can become pregnant as early as six months old and bear multiple litters of piglets yearly. In the autumn, other animals such as the American black bear compete directly with feral pigs as both forage for tree mast. These are likely reasons that they reduce diversity when they invade.
In the U.S., the problems caused by feral pigs are exacerbated by the lack of predators of pigs. Predators such as bobcats and coyotes may occasionally take feral piglets or weakened animals, but are too small to challenge a full-grown boar that can grow to three times their weight. In Florida, feral pigs made up a significant portion of the Florida panther's diet. Other potential predators include the gray wolf, red wolf, cougar, jaguar, American alligator, American black bear, and grizzly bear. However, there are barriers to pig predation for each of these animals. The jaguar is extirpated from California and the Southwest. The grizzly bear, while native to most of the American West, is gone from the states that have large feral pig populations, namely Texas, Arizona, California, and New Mexico; and the species also has a very slow reproductive rate. Wolf numbers are small and expected to remain so as they slowly repopulate their range; only a few individuals thus far have been recorded as inhabiting California, in spite of thousands of square miles of good habitat. The cougar is present in most of the West, but is gone from the East, with no known populations east of Minnesota in the north, and very thin numbers east of Houston in the South. The American black bear is both predator and competitor, but in most areas probably may not impact feral pig populations enough to control them. Programs do exist to protect the weakened numbers of large predators in the U.S., but it is expected to take a very long time for these animals to naturally repopulate their former habitat.
By the early 2000s, the range of feral pigs included all of the U.S. south of 36°
north. The range begins in the mountains surrounding California and crosses over the mountains, continuing consistently much farther east towards the Louisiana bayous and forests, terminating in the entire Florida peninsula. In the East, the range expands northward to include most of the forested areas and swamps of the Southeast, and from there goes north along the Appalachian Mountains as far as upstate New York, with a growing presence in states bordering West Virginia and Kentucky. Texas has the largest estimated population of 2.5–2.6million feral pigs existing in 253 of its 254 counties, and they cause about $50million in agriculture damage per year.
Hunting in the United States
To control feral pig numbers, American hunters have taken to trapping and killing as many individuals as they can. Some, in Texas, have even turned the trapping and killing of razorbacks into small businesses. The meat of wild pigs may be suitable for human consumption; around 461,000 animals killed in Texas between 2004 and 2009 were federally inspected and commercially sold for consumption.Legal restrictions on methods of hunting are lax, as most state departments of wildlife openly acknowledge feral pigs as an ecological threat and some classify them as vermin. For example, the Wisconsin Department of Natural Resources considers them unprotected wild animals with no closed season or harvest limit, and promotes their aggressive removal.
Shooting pigs from a helicopter, called heli-hogging, is legal in Texas, and can be an effective method, killing as many as 9 to 27 animals per hour. Helicopters can cost from $400 to $1000 per hour to operate. These costs are managed by selling seats on these helicopter flights to recreational hunters; Texas law only requires that those buying a helicopter hunt be in possession of a hunting license. The method relies on the helicopter flushing pigs into the open where they can be targeted. In some areas, such as the Piney Woods, this may not be possible because of vegetation.
Hunting with dogs is permitted and very common; it has been practiced in the Southeast for generations. Competitions for producing the fastest bay dogs are prevalent in the South, with Uncle Earl's Hog Dog Trials in Louisiana a popular example, held every summer since 1995. Preferred scent dogs for catching feral pigs mostly are native breeds, and include the Catahoula Leopard Dog, the Blue Lacy, the Leopard Hound, all six of the Coonhound breeds, and the Blackmouth Cur.
Catch dogs typically are American Pit Bull Terriers and their crosses, the Catahoula, the Dogo Argentino, a dog used for the same purpose in South America, and American Bulldogs; the first of these has been put back to work as a utility breed over the past 30 years and its tenacity on the hunt and undying loyalty to protect its master have made it a popular asset. The method of hunting has little variation: usually, the hunter sends out bay dogs trained to chase the pig until it tires and then corner it; then a bigger catch dog is sent out to catch and hold down the pig, which may get aggressive, until the hunter arrives to kill it.
No single management technique alone can be totally effective at controlling feral pig populations. Harvesting 66% of the total population per year is required to keep the Texas feral pig populations stable. Best management practices suggest the use of corral traps which have the ability to capture the entire sounder of feral pigs. The federal government spends $20million on feral pig management.
In February 2017, Texas Agriculture Commissioner Sid Miller approved the use of a pesticide called Kaput Feral Hog Lure, which is bait food laced with warfarin.