North America’s feral pig
problem concerns us all

Responsible for costly agricultural damage and a threat to ecosystems and native biodiversity

By Irwin Rapoport

September 21, 2023

The increasing number of feral pigs and “super pigs,“ a deliberate crossbreeding of domestic pigs and wild boar in Western Canada, are a major problem in Canada and the United States. The U.S. already has a serious feral pig issue but with super pigs now crossing into North Dakota from Saskatchewan and Alberta and eastward in Canada, the threat has compounded.

Feral pigs in North America, Australia, and other countries are responsible for costly damage to the agricultural sector and pose serious threats to ecosystems and native biodiversity.

Several varieties of fresh vegetables have been recalled over the years due to E. coli contamination by feral pigs. The United States Department of Agriculture web site describes the many impacts caused by these intelligent and highly adaptable creatures. They are voracious eaters and consume vast quantities of freshly planted seeds, crops at various stages of growth, and wild foods daily.

According to research conducted by the USDA in 2022, feral pigs are found in 31 American states and several Canadian provinces, including Quebec and Ontario.

They are omnivores that impact wildlife by consuming fawns, bird eggs, and hatchlings, and their searches for food wreck fragile ecosystems already under duress when they dig up the ground.

According to research conducted by the USDA in 2022, feral pigs are found in 31 American states and several Canadian provinces, including Quebec and Ontario. Populations are growing by leaps and bounds as females can breed as early as six months.

Scientists and researchers, various levels of government, organizations representing farmers and the agriculture industry, wildlife biologists and conservation authorities, and medical authorities are investing considerable resources into finding ways to contain the problem with the hope that the impacts of feral pigs can be minimized. Few believe that this invasive species could be permanently eradicated.

Hunting is one means of managing feral pigs but it is time-consuming and inefficient and does not make a serious dent in overall populations.

Image: Hillebrand Steve, U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons

Aaron Sumrall, Ph.D., Director of Outreach, Education, and Research at Pig Brig Trap Systems responded to some questions concerning feral pigs and their impact.

WM: There have been feral pigs in the U.S. and Canada for centuries, but when did the problem reach the point where it has become serious in terms of damage to farmers, wilderness areas, native flora, and fauna, and as a spreader of diseases to livestock and contaminators of produce in the field? Do we have any statistics in terms of the damage they cause?

Sumrall: There are some pulse points throughout history indicating more rapid increases than customary. The most recent occurrences of population increase were observed on and after the Great Depression, during and after WWII, and since.

At the time of the Great Depression, property was held in large tracts with single-family ownership leading owners to look for additional income. As in any economic downturn, some people continue to have expendable income and are willing to pay for their hobbies. Large acreage landowners took advantage of leasing out hunting rights to supplement the family income and imported additional feral pigs (Russian boar) for increased hunting opportunities.

‘At the time of the Great Depression… Large acreage landowners took advantage of leasing out hunting rights to supplement the family income and imported additional feral pigs (Russian boar) for increased hunting opportunities.’

– Aaron Sumrall, Ph.D., Director of Outreach, Education, and Research, Pig Brig Trap Systems

The next major spike in population occurred during and after WWII. Many of the men and women called to service came from rural America and were doing their part to hold feral pigs in check by using them as a source of low-to-no-cost food for the family. During the war, the pressure placed on feral pigs was removed, allowing the population to skyrocket. Following WWII, the economy was exceptionally good, resulting in men and women returning from the war and taking jobs in urban areas, which continued to reduce the pressure placed on the species. That reduced pressure continued well into the 1980s and early 90s.

Until recently, feral pigs were observed as merely a rural or agricultural issue, but that has quickly begun to change. Research indicates that feral pigs are responsible for economic damages of over $2.5 billion annually. Most of the damage is focused on agriculture production, which is felt directly at the farm level but passed on to every consumer of produce, livestock, timber, textiles, etc. In addition to the economic catastrophe, native flora and fauna communities are being decimated, with feral pigs being the cause of species extinction or endangerment.

WM: How many feral pigs do we have in the U.S. and Canada, and are the numbers growing? How far north can feral pigs live, and to what extent can they tolerate the cold? What is the lifespan of a typical feral pig?

Sumrall: The estimated population of feral pigs in the United States is above six million. The Canadian population is tough to assess due to vast amounts of inaccessible land. However, feral pigs occupy five Canadian provinces, and the population is growing.

Image: Canadian Council on Invasive Species

Feral pigs are capable of living as far north as they can find adequate food resources. The wildlife rule that explains this is Bergmann’s Rule. This rule outlines that as a species moves more northerly, you will see animals with larger bodies, shorter legs, and smaller ears compared to their southern counterparts. The reason for this is to conserve body heat.

We must also remember that a major source of feral pigs is in Europe and Russia, where temperatures are life-threatening. In such conditions, feral pigs will remain under blankets of snow, using it as an insulator while members of the sounder (group of feral pigs) huddle together to conserve heat.

The average lifespan of feral pigs is four to five years. Some individuals live beyond ten years of age but the average is driven down by the high piglet mortality rate. Many piglets die in their first year of life, thus resulting in an overall low average life span.

WM: Are feral pigs evolving into distinct species, and to what extent have they become part of the ecosystem? Will the super pigs from Canada become an added problem? Is there a tipping point where we will no longer be able to control their numbers or eliminate them completely?

Sumrall: Natural selection influences the phenotypic traits of feral pigs. We must remember that the term “feral” means that a species began as a domestic and was then thrust into the wild. Knowing this, after only three to four generations, we begin to see traits of domestic pigs giving way to traits that fit the environment. Domestic pigs are quick-growing, large-framed, lumbering giants but after a few generations, we see the species being much slower-growing, smaller-framed, and built to travel with low energy input.

The reason for such a transformation is directly related to nutrition. Domestic pigs are fed by a farmer and require limited activity. Feral pigs depend on nutrition that is much more cyclical, for which a slower-growing body is more suited. This is why in many circles the term “feral” is being replaced with “wild.”

‘Hunting is nothing more than recreational in terms of controlling feral pigs. Typical hunting is with conventional firearms and is only successful in removing very low numbers…’

– Aaron Sumrall, Ph.D., Director of Outreach, Education, and Research, Pig Brig Trap Systems

The challenge that the Canadian pigs represent more urgently is their expansion southward. With feral pigs dispersed across five Canadian provinces, moving south is imminent. Currently, we have breeding populations of feral pigs in more than 35 states but this southern movement will cause the number of breeding populations in the U.S. to jump quickly. Eradicating feral pigs from the landscape is likely never to happen. They have become embedded in the landscape. Managing populations is likely as good as it will get unless major steps are taken.

WM: To what extent is hunting reducing their numbers, and do the pigs know that humans are hunting them? How would you describe their intelligence and are they learning how to avoid hunters?

Sumrall: About intelligence, feral pigs are perceived to be second only to humans and hominids. Hunting is nothing more than recreational in terms of controlling feral pigs. Typical hunting is with conventional firearms and is only successful in removing very low numbers, yet, it educates the others in the sounder about human activity and how to respond to human pressure. Instances of firearms being used with thermal technologies and suppressors for the night shooting of feral pigs can see successes. Such technologies can be successful in removing small sounders.

Image: Canadian Council on Feral Species

WM: Compared to hunting, how effective are corral-trap systems in eliminating local populations of feral pigs? Have the pigs figured it out yet, and do some avoid it?

Sumrall: Research indicates that all corral-trap systems are much more efficient than hunting, so trapping should be the foundation of all feral pig eradication efforts. The corral-trap is highly effective in removing large numbers of feral pigs in a very short period. In concept, it is like a fish trap in that feral pigs funnel themselves into the trap but cannot find a way out.

Hunting is a labour-intensive and time-consuming way to remove a small portion of feral pigs while the corral-trap system removes large numbers of feral pigs as you sleep. It does not require the trapper to activate a trigger and is extremely ethical regarding captured feral pigs.

‘Research indicates that all corral-trap systems are much more efficient than hunting, so trapping should be the foundation of all feral pig eradication efforts.’

– Aaron Sumrall, Ph.D., Director of Outreach, Education, and Research, Pig Brig Trap Systems

WM: In your view, are state, provincial, and federal governments taking the problem seriously, and have they asked you to supply systems to help control feral pig populations? Are they working together to come up with effective solutions?

Sumrall: Twenty years ago, I would have said absolutely not. Huge strides have been and continue to be made at all levels of government. Locally, there are many counties, parishes, and municipalities providing incentives to remove feral pigs from the landscape. States such as Alabama and Louisiana have implemented state-level efforts through cost-share programs for farmers, ranchers, and land managers with amazing results.

Other states, including Texas, and Oklahoma, are actively engaged in pilot programs to determine the best course of action in their particular state. Strides at the federal level have been observed most clearly in the Federal Farm Bill beginning in 2018 when funding was included to focus specifically on eradication, education, and research focused on feral pigs.

The Center for Disease Control and the Department of Health and Human Services have each included feral pigs in their focus as a human safety issue related to disease and food contamination concerns. This is expected to continue with the 2023 Farm Bill and other state and local funding sources.

WM: What type of damage are feral pigs causing to wildlife populations, and are they responsible for local and complete extinctions of flora and fauna? To what extent are they destroying ecosystems and forests?

Sumrall: The impacts of feral pigs are catastrophic to native flora and fauna both directly and indirectly. Feral pigs have been identified as the cause of the extinction of local species worldwide, including the United States, with a growing number of pig-affected species being classified as endangered or threatened. In addition to direct impacts, feral pigs are indirectly impacting ecosystem habitats depended on by countless native species. Though, in this instance, feral pigs may not be the direct vector of extinction, endangerment, or threatened status, those species will dwindle as their life-sustaining habitat is lost to feral pig damage.

‘The impacts of feral pigs are catastrophic to native flora and fauna both directly and indirectly. Feral pigs have been identified as the cause of the extinction of local species worldwide…’

– Aaron Sumrall, Ph.D., Director of Outreach, Education, and Research, Pig Brig Trap Systems

WM: To what extent can native predators like bears, wolves, coyotes, wolverines, mountain lions, alligators and crocodiles, birds of prey, and others reduce feral pig populations?

Sumrall: Native predators have very little impact on feral pig populations. In almost every case, after a feral pig reaches weaning size/age, humans are the only remaining population managers. Native species shy away from medium to large feral pigs due to the species fighting tirelessly against predators, which prefer food that doesn’t fight back so aggressively.

WM: Once captured, are most feral pigs slaughtered humanely, and is there a market for their meat domestically and for export, as well as pet food?

Sumrall: Individual state laws indicate the legal options for captured feral pigs. Some states allow for the transportation of feral pigs to “market” in the form of buying stations while other states require that captured feral pigs be dispatched at the trap site. True feral pigs are not found on the shelves of your local grocery store because the meat has not been state-inspected. Feral pigs delivered to buying stations are processed and exported for human consumption, with a very small proportion making it into pet food.

WM: When native wildlife is caught in the traps, can they be saved and released?

Sumrall: Non-target species such as raccoons and bears will simply climb over the net. Rarely, when deer find their way into the trap, they can simply jump out, or the trapper can come to the trap site after dark and lower the trap, allowing the animal to leave. In the very rare instances where antlered bucks get caught in the net, the trapper can untangle the deer.

For more information about feral pigs, visit :

canadainvasives.ca/wild-pigs

cwhc-rcsf.ca/invasive_pigs

In French: sangliersenliberte.com

Feature image:  Kevin Jackson – Unsplash

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Irwin Rapoport is a freelance journalist with Bachelor’s degrees in History and Political Science from Concordia University.