Feral swine (Sus scrofa)

Synonyms: Sus scrofa domesticus, Sus scrofa scrofa

Common Names: Feral hog, feral pig, wild pig, wild hog, wild boar, Eurasian wild boar, Russian boar, razorback

Description:

Feral swine (Sus scrofa) are wild-living pigs ? a mix of escaped domestic hogs, released Eurasian wild boar, and their hybrids ? and are one of the most destructive invasive animals in North America [1][2]. Brought from Eurasia as livestock and later spread by people for hunting, they root up crops, lawns, and natural areas, prey on and compete with wildlife, and carry many diseases [1][2]. MISIN tracks them because populations grow explosively, the animals can be dangerous, and moving or releasing pigs is the main way they spread [2].

Identification:

Feral swine look much like the farm pigs they descend from, but tougher and wilder. Adults commonly weigh from about 75 to 250 pounds (some far more), stand up to roughly 3 feet tall at the shoulder, and reach about 5 feet long [1]. They are covered in coarse, bristly hair that can be black, brown, red, white, or a mix, and their piglets are often striped or spotted, fading as they grow [1]. Compared with domestic hogs, feral swine are leaner and more muscular, with a thicker hide, a longer snout, and longer tusks [1]. They usually travel in family groups called sounders [2].

Feral swine are active year-round, often moving at dawn, dusk, and night, so you may see their damage before you see the animals [2]. The most obvious sign any time of year is the ground: large areas churned up as if a rototiller went through, plus muddy wallows and rubbed tree trunks [2]. Do not approach feral swine ? they can be aggressive, especially a sow with young (see Impact) [2].

At-a-glance cues:

1. Large, lean, bristly-haired pigs (about 75?250+ lb), often in family groups [1][2]
2. Longer snout, longer tusks, and thicker hide than domestic farm hogs [1]
3. Striped or spotted piglets [1]
4. Ground churned up as if rototilled, with muddy wallows and rubbed tree trunks [2]

Habitat:

Feral swine are extremely adaptable and live in many habitats ? forests (especially oak woods), wetlands and stream bottoms, brushlands, grasslands, and farmland ? wherever there is food, water, and cover [1][2]. They are mainly held back by cold, snowy winters, since deep snow makes it hard for them to travel and find food [2]. This adaptability lets them establish almost anywhere they are released [1].

The species is native to Eurasia and North Africa [1]. Every free-living pig in North America is non-native ? descended from domestic hogs brought over as livestock, from Eurasian wild boar released for hunting, and from crosses of the two [1][2]. Feral swine are now estimated at more than six million animals across at least 35 U.S. states and are still expanding their range [1].

Reproduction:

Feral swine spread in two ways, and people drive the worst of it. The animals move on their own across the landscape, but the long-distance jumps come from people moving and releasing pigs ? often illegally ? to start new herds to hunt [2]. That is why pigs suddenly appear in places far from any existing herd [2].

Once established, they multiply fast. Where conditions allow, sows breed year-round and can raise more than one litter a year, with litters of roughly 4 to 12 piglets, and the young can begin breeding before their first birthday [1][2]. Because of this, a population can double quickly, and wildlife managers estimate that around 70% of a feral swine population must be removed each year just to keep it from growing [2]. For control, that means early reporting of new, small groups is far more effective than waiting until a herd is large and established [2].

Impact and Damage:

Feral swine are one of the few invasive species that can directly threaten people. They can be aggressive when cornered or when a sow is protecting piglets, and they carry roughly 30 diseases and 40 parasites ? including brucellosis and others that can spread to people, pets, and livestock ? so they should never be approached, and carcasses should not be handled without gloves and care [1][2]. On a property, they root up and destroy lawns, gardens, food plots, crops, and pastures, often overnight, and damage fences and water sources [2].

In natural areas the damage is severe and wide-ranging. Their rooting and wallowing tear up the soil and native plants, muddy streams and wetlands, and speed erosion, while the pigs also eat the eggs and young of ground-nesting birds, reptiles, and amphibians and compete with native wildlife for acorns and other food [1][2]. They can also carry serious livestock diseases, including a threat of introducing African swine fever, which makes them a danger to agriculture as well [1]. Across the United States, feral swine are estimated to cause damage in the billions of dollars each year [1][2].

Similar species:

Domestic and free-ranging farm pigs (also Sus scrofa) are the main look-alike, since feral swine descend from them. Farm pigs tend to be heavier-bodied, more lightly haired, and tame, often with short tusks, while feral swine are leaner and more muscular, with coarse bristly hair, a longer snout, longer tusks, and a wary, wild manner. Pigs living loose and unmanaged are effectively feral swine regardless of their origin.

Black bear (Ursus americanus), at a distance, can be mistaken for a feral hog because both are large, dark animals that dig and root in the ground. A bear is told apart by its rounded ears, lack of a pig-like snout and tusks, longer legs, and short tail, rather than the long snout, tusks, and straight tail of a feral hog.

Monitoring and rapid response:

Signs to watch for:

1. Large areas of soil churned up as if rototilled, plus muddy wallows and mud-rubbed tree trunks [2]
2. Large, lean, bristly pigs ? often in family groups ? usually active at dawn, dusk, or night [1][2]
3. Cloven (two-toed) tracks larger and rounder than deer tracks, and sudden overnight crop, lawn, or pasture damage [2]

What you can do:

1. Do not approach feral swine ? they can be aggressive, especially a sow with piglets ? and keep children and pets away [2].
2. Never buy, move, release, or relocate pigs for hunting; this is the main way feral swine spread and is illegal in many places [2].
3. Report sightings and rooting damage promptly to your state wildlife or agriculture agency and to MISIN (below) ? catching a new, small group early is far more effective than waiting [2].
4. Protect your property by securing garbage, pet and livestock feed, and fallen fruit, and by using sturdy fencing where practical; if you must handle a carcass, wear gloves and wash up afterward because of disease risk [1][2].
5. Landowners and crews should not try to shoot out a herd piece by piece, which scatters the pigs and makes control harder ? instead, coordinate with the USDA feral swine program and state agencies, which remove whole family groups at once [2].

When to call a professional:

1. Any feral swine sighting or damage ? contact your state wildlife or agriculture agency or the USDA APHIS feral swine program, since safe, effective removal is coordinated and regulated, not a do-it-yourself job [2].
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. USDA National Invasive Species Information Center. Wild Boar (Sus scrofa). invasivespeciesinfo.gov
2. USDA Animal and Plant Health Inspection Service (APHIS). Feral Swine: Managing an Invasive Species. aphis.usda.gov
3. Michigan Department of Natural Resources. Invasive Species: Russian Boar (Sus scrofa). michigan.gov/invasives

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