Feral Swine: Damages, Disease Threats, and Other Risks, Publication

FERAL SWINE: Damages, Disease Threats, and Other Risks
What Are Feral Swine?

Why Are They a Problem?

Feral swine (also called wild pigs, Eurasian boar, or feral hogs) are

The damage feral swine cause is wide-ranging and far-reaching. With

a harmful and destructive invasive species. They are not native

populations spreading throughout the United States, this invasive animal—

to North America. Early explorers and settlers first brought feral

with few natural predators—negatively impacts everything from agriculture

swine into the United States in the 1500s as a source of food. The

and the environment to human health and public safety. Feral swine can

number of feral swine grew further after that; they were introduced

multiply faster than any other large mammal; females begin breeding at

repeatedly in different areas of the country and also started

about 8 months and can produce 2 litters of 4–12 piglets every 12–15

crossbreeding with escaped domestic pigs. Today, their geographic

months. The main reasons for their expanding range include accidental

range is quickly expanding as their populations continue increasing

escapes or intentional releases from fenced facilities and people moving

nationwide. Over 6 million feral swine can now be found across

them illegally to new areas. Damages, costs, and risks from feral swine will

more than 35 States.

only keep rising as their populations continue to expand across the country.

Agriculture
Feral swine damage crops and destroy fields (reducing crop yield) with their feeding, rooting, trampling,
and wallowing behaviors. They usually target sugar cane, corn, grain sorghum, wheat, oats, peanuts, and
rice, among others. Vegetable and fruit crops, such as lettuce, spinach, melons, and pumpkins, are also
attractive to them. Feral swine can also impact the regeneration of forests. By consuming seeds, nuts, and
seedlings and damaging land, they keep new trees from growing and can stunt the growth of existing trees.
Feral swine can spread diseases to livestock. This causes economic losses such as decreased production,
reduced feed efficiency (less food intake affects animal growth and overall health), lower reproductive
success and increased mortality in the herd, and higher costs for veterinary care. Feral swine are
omnivorous, meaning they eat just about anything. They can kill calves and lambs, and adult livestock are
vulnerable to predation while giving birth.
In addition, feral swine degrade pasture grasses; eat, contaminate, and destroy livestock feed; and
damage farm property, such as fences, water systems, irrigation ditches, troughs, and levees.

Health and Public Safety
Feral swine can carry at least 30 diseases and nearly 40 types of parasites that may affect
people, pets, livestock, and wildlife. Some diseases, such as pseudorabies, are fatal to cats
and dogs that may be exposed from direct contact with a feral swine carcass. Feral swine
can also transmit foodborne illnesses, such as E. coli, toxoplasmosis, and trichinosis. In some
areas, feral swine have been the cause of elevated waterborne bacteria levels in streams and
irrigation canals, which is another risk for human health.
When in roadways or at airports, feral swine can collide with vehicles and aircraft, putting the
safety of drivers, pilots, and passengers at risk. Other public safety risks arise when feral swine
are in urban and suburban areas. As they become less afraid of people over time, they have
shown aggression toward golfers, picnickers, and others. This behavior is more of a problem
when they associate people with food because of handouts and improper waste disposal. In
addition, feral swine may be aggressive to dogs and other pets.

Animal and Plant Health Inspection Service

FERAL SWINE: Damages, Disease Threats, and Other Risks
Natural Resources
Feral swine cause widespread damage to natural resources.

turtles, amphibians, and ground-

They consume large amounts of vegetation; destroy plants with

nesting birds). Feral swine will

their rooting, soil compaction, and wallowing behaviors; and in

destroy nests and eat the eggs of

some areas, may eat or uproot protected, sensitive, unique, or

alligators, other reptiles, and ground-

rare plants. Often, the damaged land then becomes vulnerable

nesting birds, such as quail, turkey,

to erosion and non-native, invasive plants.

and shorebirds. And because feral

In addition, soil disturbance and vegetation loss from feral swine
damage increases erosion and degrades water quality. Siltation
(a form of water pollution) and contamination in streams and
coastal areas with swine activity have contributed to declines in
aquatic organisms, including freshwater mussels and insects.
Wildlife are impacted by feral swine, too. Since their diets
overlap, feral swine and native wildlife end up competing for
important and limited natural food sources, such as acorns and
other forest tree nuts. Feral swine also reduce the amount of
food available in general—they consume seeds, plants, and
small animals (including insects, earthworms, voles, shrews,

swine prefer wet environments, they
compete with native wildlife for
scarce water resources during dry
seasons. Feral swine can also have
negative effects on threatened
and endangered species and
their habitats.
Lastly, feral swine can spread
diseases to wildlife, some of which
can be fatal. The damage they cause also tends to increase mosquito habitat; this,
in turn, can increase the prevalence of avian malaria and avian pox, which threaten
the health of native birds.

Property
If feral swine are in the area, they can quickly ruin homeowners’ efforts to maintain and improve their
properties. Destroyed vegetation and wallows reduce the aesthetic value of private properties, as well
as public parks and recreational areas. Feral swine foraging, rooting, and wallowing also damages
landscaping, golf courses, recreational fields, cemeteries, parks, lawns, and other natural areas.
In addition, adult feral swine weigh from 75 to 250 pounds on average, with some weighing considerably
more. As a result, collisions with vehicles and aircraft can mean costly property damage.

Cultural and Historic Resources
Other resources affected by feral swine
include national historic sites, tribal sacred
sites and burial grounds, cemeteries, and
archaeological sites and digs. Feral swine
damage structures, destroy vegetation,
and disturb soil and land. This can

Want To Learn More?
Wildlife Services, part of the U.S. Department
of Agriculture’s Animal and Plant Health
Inspection Service, is on the front lines in
the battle with this invasive animal.

seriously degrade the significance and

If you have questions or need help dealing

historic integrity of these sites. Foraging

with feral swine, call us at 1-866-4USDA-WS or go to

and habitat damage by feral swine can

www.aphis.usda.gov/wildlife-damage/stopferalswine.

also negatively impact the distribution
and abundance of plants and animals
that may be used for traditional purposes
(for example, sage for Native American
ceremonies or herbal medicines).

The U.S. Department of Agriculture is an equal opportunity provider,
employer, and lender.
Program Aid No. 2195b
Issued April 2016