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 

expanded 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 farreaching 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 of approximately 6 million and distributed across more 

than 31 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, signs, 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 

(white-tailed, 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 Revised May 2020

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.