DAYTON, Ohio––Hitting a guard rail, then flipping upside down in a ditch alongside Ohio State Route 35, a tractor-trailer rig hauling 2,200 piglets from farrowing in South Carolina to finishing in Indiana split open on the night of June 8, 2015, “killing about half of the 2,200 piglets on board and sending hundreds of survivors fleeing into the nearby woods,” WLWT-Cincinnati reported.
“Quite a few pigs got out and ran,” Xenia Township fire chief Dean Fox told WLWT reporter Jackie Congedo. “They’re in the woods. I don’t think we’ll ever get all of them, I really, really don’t. We’ll try as hard as we can to retrieve all of them, but we probably won’t retrieve all of them,” Fox said.
“Scattered into a wooded area”
Added WRGT-Dayton, “Police and fire agencies from surrounding areas rounded up the piglets, who scattered into a wooded area by the side of the road. The recovered animals were taken to nearby fairgrounds to be given water by volunteers.”
The Dayton Daily News reported that the surviving piglets were transported on to their destination in the early morning of the following day.
The accident exemplified how feral pigs have just within a few decades come to inhabit most of the U.S.
As of 1982, only 17 U.S. states were known to have feral pigs. Today, according to the U.S. Department of Agriculture, at least 39 states have endemic feral pigs.
$20 million for feral pig eradication
Blaming feral pigs for $1.5 billion a year in economic damage, including $800 million in damage to crops, farm facilities, and livestock, the USDA in 2014 committed $20 million to feral pig eradication, including $1.5 million to fund research into the use of sodium nitrate as a feral pig poison. The research consists chiefly of trying to develop baits that will kill 90% of penned groups of pigs at the USDA research center in Fort Collins, Colorado.
The wildlife agencies of 41 states have now all but exempted pig hunters from most of the laws that govern other forms of hunting, on the pretext that pigs are a non-native invasive nuisance.
Technology exists to control and perhaps eliminate unwanted feral pig populations without bloodshed, but has yet to be widely deployed. One promising approach is the use of immunocontraceptives.
Immunocontraceptives based on porcine zona pellucida, a slaughterhouse byproduct called PZP for short, are now widely used to control wild horse herds, and are the subject of litigation recently brought by Friends of Animals to try to stop wild horse population reductions. PZP is also used to control zoo animal fecundity, and–experimentally–urban deer. (See http://www.animals24-7.org/2015/05/22/sex-drugs-wild-horses/.)
“PZP doesn’t work on any of the species in Suidae,” the mammal order including pigs,” said immunocontraceptive developer Jay Kirkpatrick, of the Science & Conservation Center in Billings, Montana. “That is because the protein that constitutes the vaccine comes from pigs and they will not recognize it as ‘foreign’ and make antibodies against it. There are several GnRH vaccines, however, that will work in pigs,” Kirkpatrick told ANIMALS 24-7.
Zona pellucida cells from another species would be needed to immunocontracept pigs, but finding an appropriate source of cell tissue appears to be a relatively simple scientific problem, since there are few animals, including humans, whose reproductive biochemistry is better understood than that of pigs.
GnRH vaccines “are directed against the brain transmitter substance known as gonadotropin releasing hormones,” Kirkpatrick explained. “One is Improvac, a Pfizer product made in South Africa. Another is Equity, made in Australia. Another is GonaCon, a product developed by the USDA National Wildlife Research Center for deer. And there is another developed for feedlot cattle, BoPriva, but I don’t know for sure if this one works in pigs. Only GonaCon is licensed in the U.S.”
Feral pigs have occurred in remote parts of the U.S. for centuries, but until the late twentieth century had not significantly expanded their population and range in a hundred years.
Often their numbers and range were limited by geography.
Feral pigs, for example, emerged as an early campaign focus of the Fund for Animals, during the 25-year effort of the U.S. Navy, Nature Conservancy, and National Park Service to extirpate pigs from San Clemente Island and the Channel Islands, off the southern coast of California. Some of the island pigs were eventually trapped and transported to the Black Beauty Ranch sanctuary in northeastern Texas.
Later, in 1991-1993, PETA cofounder Alex Pacheco exposed the tactics used by Nature Conservancy tactics to kill feral pigs in Hawaii, including aerial shooting and setting snares in which caught pigs died slowly, over many days.
At about the same time In Defense of Animals protested against cruel methods of pig extermination in the hills surrounding San Francisco Bay.
The feral pigs of the Channel Islands, coastal California foothills, and Hawaii were all descendants of pigs brought by early European settlers––mingled, in the case of the Hawaiian pigs, with ancient Polynesian stock. Each pig population had maintained a presence documented for 100 years or more. But the island pigs had no way to colonize habitat beyond the islands, while the coastal California pigs were caught between the Pacific Ocean to the west, San Francisco Bay to the north, and arid mountains they could not cross to the south and east.
Such was also the history of other scattered feral pig populations, for example the iconic wild razorbacks of the Ozarks, whose ancestors escaped from homesteaders in the early 19th century. While razorbacks spread east and south, the Ohio and Mississippi rivers kept them from moving north and west.
Some of the feral pigs of today have been translocated to new habitat by pig hunters trying to increase their hunting opportunities.
In March 2015, for example, Samuel E. Edwards, 65, of Broken Arrow, Oklahoma, was charged with illegally importing 117 feral pigs from Texas.
“More than half of the feral swine tested positive for pseudorabies––a viral disease that can be fatal to various domestic animals and livestock, the Oklahoma Department of Agriculture, Food and Forestry said. Several also tested positive for brucellosis, which can affect livestock and humans,” reported Tulsa World staff writer Samantha Vicent.
Spread by pig industry
Most of the fast-proliferating feral pigs of today, however, are healthy accidental byproducts of commercial pork production.
Their lineage may include some genetics from older feral pig populations begun with the Spanish explorer Hernando de Soto. Often blamed for introducing feral pigs to North American, de Soto landed in Florida in 1539 with 620 troops and 200 pigs meant to feed the troops. About half the men died during the ensuing three-year trek across the South and down to Mexico City. Many of the pigs escaped.
More than 450 years of pig farming elsewhere in North America has also contributed to the present feral pig gene pool.
But feral pigs did not achieve rapid territorial expansion until the advent of factory farming and long-haul trucking to move pigs to market.
Value of lost pigs declined
Somewhat surprisingly, USDA data shows that the numbers of pigs on U.S. farms at any given time now is not significantly different from the numbers on farms in 1900: 50-odd million then, 50-odd million now.
There were actually more pigs on farms in 1940: just over 61 million. However, since 1940 the total number of farms has dropped by two-thirds, the farm labor force has dropped by more than 80%, and total number of pigs slaughtered has almost doubled, because the average time taken to raise a pig to slaughter weight has been cut in half.
In addition, in inflation-adjusted dollars, a pig now sells for a third less than in 1940. As the value of each pig has fallen, the number of workers available to try to recover each escaped pig has plummeted, and the number of pigs in transit at any given time has soared.
With more pigs on the road at all times, hauled in much larger trailers than a generation ago, the opportunities for pigs to get loose and introduce themselves to new habitat have never been greater.
Trucking accidents from which pigs might escape occur at a reported rate of about 60 per year, involving as many as 10,000 pigs altogether, according to data included in U.S. Highway Accidents Involving Farm Animals, a compilation taken from news reports, published by Farm Sanctuary in June 2006. By now, nearly a decade later, the numbers may be higher.
But most pig-hauling accidents don’t make news, Richmond Times-Dispatch staff writer Bill Geroux discovered in April 2005, while investigating an incident in which about 180 pigs spilled from a toppled trailer.
“The confused animals rooted in the grass or scrambled into nearby woods,” Giroux reported. “Some of them lay squealing in the wreck. One hog set off down the narrow two-lane blacktop, where morning commuter traffic came to a halt. About 30 hogs lay down for a nap in the sunshine between two houses.
“It happens all the time”
“Every day,” Giroux continued, “dozens of trucks packed with 150 or more hogs converge on Smithfield’s two large slaughterhouses from hog farms in Southside Virginia and North Carolina. And every year, a few of those trucks plunge off the rural highways near the plants.”
Said Smithfield spokesperson Jerry Hostetter, “I hate to admit it, but it happens all the time.”
“As Smithfield’s production has grown,” Giroux recounted, “the company has established a rapid-response team to recapture hogs.”
Most pigs who escape from wrecked trucks are soon caught. Most of the pigs aboard the trucks have little or no experience of freedom, and no idea how to feed themselves as wild animals.
Still, if even 3.5% of all the pigs involved in documented transport accidents get away and survive long enough to raise litters, their net contribution to the feral population would be the equivalent of all of de Soto’s pigs escaping to breed each and every year.
Breadth of distribution
More important than the number, however, is the breadth of distribution. De Soto’s pigs could only expand into habitat adjacent to the habitat they already occupied. Until the advent of transporting pigs by railway, in the late 19th century, there was no faster way than walking for a pig to colonize new territory. Natural boundaries such as waterways and high mountains were rarely breached.
Even in the railway era, large numbers of pigs were moved only along a handful of routes. Pigs were raised mainly in the South and the grainbelt states, close to food sources.
Today, pigs by the tens of thousands are raised in confinement barns in the Dakota badlands and the Rocky Mountains. Pigs are trucked throughout most of the continental U.S., across all former barriers to pig travel.
As accidents occur more or less randomly, the result is a continent-wide experiment in releasing a few pigs here and a few there. The optimum feral pig habitats are being found and populated, if only by chance. Instead of feral pig populations marching predictably from one regional stronghold to the next, they are capturing territory like paratroopers who secure wherever they land.
But if feral pigs are all descended from factory-farmed pigs, why do they look like European wild boars? And how are they reproducing, when most factory-farmed males are castrated?
Indeed, most factory-farmed male pigs could not contribute to a growing feral population–but about half of the factory-farmed pigs in transit at any given time are females, who readily hybridize with either males from older feral populations or European boars, now abundant on hunting ranches and also inclined to escape occasionally.
Among the many different pig strains now at large, feral pigs are conducting their own vast, uncontrolled experiment in adapting to North American habitat. Over time, the outcome may be regionally distinct feral pig varieties.
For the moment, European boar characteristics seem to be dominant. This is no surprise. Hunting ranch operators learned decades ago that hybridizing imported European boar stock with common domestic pigs would produce animals of European boar appearance but domestic pig temperament.
Further, most common domestic pigs are slaughtered so young that people who are not pig experts seldom realize how much they will resemble their European boar ancestors if allowed to reach maturity.
Pig hunting industry
The combination of the appearance of a traditional trophy species with the familiar flavor of pork has created a growing commercial pig hunting industry, especially in Texas, whose feral pig population officially exceeds two million.
“It is ironic that the wild hog market is growing with the organic market, as many people turn toward organic meat to avoid supporting the cruelty of factory farming,” commented Karen Dawn of DawnWatch in 2007, as one of the first animal advocates to notice the trend. “Indeed wild hunted animals, at least those few lucky enough to die from a clean shot, suffer incomparably less than those raised in tiny cages and trucked in unconscionable conditions to under-regulated slaughterhouses. But hunted hogs suffer horribly for hunters’ fun.”