FERAL SWINE: Impacts on Game Species

What Are Feral Swine?

Feral swine (also called wild pigs, boar, feral hogs, 

and many others) are a destructive invasive species. 

They vary in color from black to brown and even 

patchwork colors, and range in size from 75 to 250 

pounds. Feral swine belong to the family Suidae

and were introduced into the United States in the 

1500s by early explorers and settlers as a source of 

food. Over centuries, domestic pigs, Eurasian boar, 

and their hybrids have escaped, been released, 

and been reintroduced, setting the scene for the 

rapidly expanding populations we have today.

Feral swine directly impact native game species by preying on the nests, eggs, and young 

of ground-nesting birds and the young of larger animals such as deer. They compete with 

native wildlife for important food sources, displace other animals through aggression and 

competition, and can spread diseases and parasites. The most far-reaching impact feral 

swine have on game species and 

other wildlife is habitat change 

and destruction through their 

rooting, wallowing, trampling, and 

feeding behaviors. Feral swine are 

ecosystem engineers, which means 

they can change their environment 

by altering water quality and runoff in wetland environments, shifting plant composition and 

distribution in grasslands, and decreasing tree diversity in a forest. Feral swine are a risk to 

native game species such as deer, quail, grouse, turkey, and many others, as well as to the 

economic stability of businesses that depend on these game species to succeed. 

Why Are They Considered an Invasive Species? 

Invasive species are defined as plants or animals that are non-native to an ecosystem and 

often have broad negative impacts on the environment where they are introduced. With feral 

swine populations over 6 million and distributed across more than 35 States, the damage 

they cause is significant to the environment, economy, and human health. Feral swine 

damage to habitats, predation 

on wildlife, and disease 

transmission can be linked 

to the decline of nearly 300 

native plants and animals in the 

United States, including native 

game species.

Feral swine cause problems by damaging native ecosystems, preying on or 

competing with native wildlife, and spreading diseases.

• Do not relocate feral swine to new areas or transport them to other States.

• Share the knowledge; discourage transportation and spread of feral swine. 

• If you live in a State with no or low levels of feral swine, report any 

sightings, sign, or damage to wildlife or agriculture officials in your State.

What 

Can I Do?

What Is Their Impact? 

Animal and Plant Health Inspection Service
Upland Birds 

Upland game species such as 

quail, woodcock, and grouse 

are at risk from predation by 

feral swine because they nest on the ground. In addition to direct 

predation, feral swine destroy important upland game bird habitat 

by rooting up and eating native plants, allowing the growth and 

spread of invasive weeds. 

Deer

The feral swine diet consists 

largely of vegetation; therefore, 

they compete with herbivores for 

food sources. Most notably, feral swine compete with deer (whitetailed, mule, or black-tailed) for seasonal resources such as acorns 

or beech nuts. They easily disperse deer from prime feeding areas, 

will prey on fawns, and transmit diseases to which deer 

are vulnerable.

Turkey 

Wild turkeys are ground nesters, 

leaving their eggs and young 

exposed to feral swine predation. 

Additionally, feral swine compete with wild turkeys for important 

seasonal resources such as acorns. Since feral swine can eat larger 

amounts of food and digest it more quickly than turkeys, they 

easily outcompete these birds for vital seasonal food sources. 

GAME SPECIES

at Risk From Feral Swine Impacts and Damages

Furbearers 

Foxes, weasels, raccoons, and other 

furbearers prey on eggs, small mammals, 

carrion, and invertebrates, which are also 

desirable food sources for feral swine. A group of feral swine, called a 

sounder, can easily displace smaller, often independent, furbearers from 

a food source. Feral swine also carry many diseases and parasites, such 

as giardia, which may be passed on to furbearers. 

Small Game 

Feral swine outcompete small 

mammals for important seasonal 

resources such as acorns. They have 

also been known to raid the buried food caches of squirrels, leaving 

them with no stores for winter. Feral swine even actively hunt small 

mammals such as ground squirrels. Furthermore, feral swine rooting and 

feeding behaviors alter forest growth and diversity, damaging crucial 

habitat for small game animals. 

Big Game 

Feral swine feeding behaviors and 

preferences are similar to black bears, 

meaning they may compete for food 

resources such as vegetation, berries, acorns, and more. Some large 

predators, such as mountain lions, may benefit from feral swine as prey, 

but this can put them at risk of contracting the diseases and parasites 

feral swine carry.

USDA is an equal opportunity provider, employer, and lender. Photo credits: Images courtesy of USDA-APHIS Wildlife Services and U.S. Fish and Wildlife Service. 

Program Aid No. 2195e Issued October 2016

Want To Learn More?

Call Wildlife Services, a program within the U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection 

Service, at 1-866-4-USDA-WS or visit www.aphis.usda.gov/wildlife-damage/stopferalswine to learn more about the 

problems caused by this invasive animal, as well as to seek advice and assistance in dealing with feral swine.