The Invasion Of The Feral Hog

The Male Feral HogExperts estimate that Feral Hog does over $1.5 billion (2012 estimate) in damages to farms across the United States, especially in Texas and increasing annually.  Today the United States faces an on slaught of the of feral hog invasions to the point that their numbers are unmanageable and the reality of control or the cost of control is almost out of reach. Too many times, we hear the comment from state and federal agencies, “we’ll wait and see if they (the invasive species) work their way into and becomes a part of the Ecosystem”. In the case of the feral hogs they are wrecking balls to most all ecosystems they’ve invaded.

At The Heart of the Feral Hog Invasion is Texas

Feral Hog population in Texas (Green)Texas is at the epicenter of the Feral Hog invasion. As of 2012 the estimated top end of the estimated population is 4 million animals. The average Feral Hog density in Texas ranged from 1.3-2.5 hogs/square miles from reported studies. By multiplying the density estimate to the total potential suitable feral hog habitat, we estimated the number of feral hogs statewide to be between 1.8 and 3.4 million, with the average being 2.6 million. Reportedly, 79% of Texas represents “suitable habitat for the feral hog which is pretty much anywhere they call home”.

The estimated population of 4 million in Texas, 25% of the is harvested by sport hunters and eradication methods, trapping aerial gunning etc. That’s one million animals, huge number. But in order to keep the 4 million populations constant, 60-70% of the population would have to be harvested or managed annually, that’s 2.8 million critters. In short Texas and most other states are to the point they are going to BBQ their way out of the Feral Hog problem, manage maybe. But at what expense and where does the financial support come from?

The History and Background of the Feral Hog

The wild boar, also known as the wild swine or Eurasian wild pig, is a native to much of Eurasia, North Africa, and the Greater Sunda Islands. Human intervention has spread its range further, making the species one of the widest-ranging mammals in the world, as well as the most widely spread uniformly. Its wide range, high numbers, and adaptability mean that it is classed as least concern by the IUCN. The animal probably originated in Southeast Asia during the Early Pleistocene, and outcompeted other suid species as it spread throughout the Old World.

As of 1990, up to 16 subspecies are recognized, which are divided into four regional groupings based on skull height and lachrymal bone length. The species lives in matriarchal societies consisting of interrelated females and their young (both male and female). Fully grown males are usually solitary outside of the breeding season

The Origins Of The Feral Hog or Pig

Domestic pigs were first introduced to the Americas in the sixteenth century. Christopher Columbus intentionally released domestic swine in the West Indies during his second voyage to provide future expeditions with a freely available food supply. Hernando de Soto is known to have introduced Eurasian domestic swine to Florida in 1539, although Juan Ponce de León may have introduced the first pigs into mainland Florida in 1521.

The practice of introducing domestic pigs into the New World continued throughout the exploration periods of the sixteenth and seventeenth centuries.  The Eurasian wild boar, which originally ranged from Great Britain to European Russia may have also been introduced. By the nineteenth century, their numbers were sufficient in the Southern United States to become a common game animal.

2015 – Distribution of the Feral Hog in the United StatesFeral pigs are a growing problem in the United States and on the southern prairies in Canada. As of 2013, the estimated population of six million feral pigs causes billions of dollars in property damage every year in the United States, both in wild and agricultural lands. Because pigs forage by rooting for their food under the ground with their snout and tusks, a sounder (group) of feral pigs can damage acres of planted fields in just a few nights. Because of the feral pig’s omnivorous nature, it is a danger to both plants and animals endemic to the area it is invading. Game animals such as deer and turkeys and, more specifically, flora such as cactus which have been especially affected by the feral hog’s aggressive competition for resources. For commercial pig farmers, great concern exists that some of the hogs could be a vector for swine fever to return to the U.S., which has been extinct in America since 1978. Feral pigs could also present an immediate threat to “non-biosecure” domestic pig facilities because of their likeliness to harbor and spread pathogens, particularly the Protozoa Sarcocystis.

The Migration Of The Feral Hog

The south, the Feral Hog is doing very well adapting to the landscape whether its the arid flatlands and deserts of Texas or the swamp conditions and heavily wooded ecosystem of Alabama, Georgia, Carolinas to Florida. In short, the Feral Hog is extremely adaptable to all ranges of climates and terrain to call home, which is most all of the lower 48.  If they are not in your state, they will be soon if left unchecked.

The migration patterns have developed where we see an immigration of Texas hogs into Oklahoma, New Mexico and Arizona. California has they’re problems with the Feral Hog in and around the Monterey Peninsula and vineyard counties from another whole set of dynamics. Now that’s not to say the invasion is the Feral Hog sneaking across state borders. With the number of hog farms across the country, the hogs are known as escape artists and they do escape their confines. They’re not all caught and or recaptured by any means. So the feral reproduction begins. The total estimated population in the US is 8 million in 2012, today the estimate is at 10-12 million and increasing.

Feral Hog invasion into the Louisiana areaIn the early 2000s, the range of feral pigs includes all of the U.S. south of the 36°N. The range begins in the mountains surrounding California and crosses over the mountains, continuing consistently much farther east towards the Louisiana bayous and forests, terminating in the entire Florida peninsula. In the East, the range expands northward to include most of the forested areas and swamps of the Southeast, and from there goes north along the Appalachian Mountains as far as upstate New York, with a growing presence in states bordering West Virginia and Kentucky. Texas has the largest estimated population of 2.6 million feral pigs existing in 253 of its 254 counties.] Outside mainland U.S., Hawaii also has feral pigs introduced to Oahu soon after Captain Cook’s discovery of Hawaii in 1778, where they prey on or eat endangered birds and plants. The population of feral pigs has increased from two million pigs ranging over twenty states in 1990, to triple that number twenty-five years later, ranging over 38 states with new territories expanding north into Oregon, Pennsylvania, Ohio, and New Hampshire. Some of these feral pigs have mixed with escaped Russian boar that have been introduced for hunters from the early 1990s.

Arizona and New Mexico are currently studying the Feral Hog populations.  Arizona is looking at the problem, New Mexico actually engaging in several eradication methods.

The Reproductive Habits Of The Feral Hog

The Reproduction Issues of Feral HogsFemale feral hogs reach sexual maturity as young as 3-4 months of age; however, most wild sows reach puberty by the time they are one year old. Females of this species are polyestrous, being able to come into estrus every 18-24 days if they are not successfully bred.

The ovulation rate typically averages 7-8 but can range from 3-15. The feral hog’s gestation period averages 112-120 days and can vary from 100-140 days. Fetal litters in feral hogs average 5-6 embryos/fetuses and range from 1-14. The observed intrauterine mortality in this species is approximately 30%. In general, fetal litters are often male-biased, but this sex composition is normally not significant.

There is also an observed shift from male-biased to female-biased composition as the litter size increases. The ovulation rates, litter sizes, and pregnancy rates all increase with the sow’s age. Both the nutritional input and reproductive output levels in feral sows are also positively correlated. Sows build a farrowing nest within 24 hours prior to giving birth to provide protection for their offspring. This is true even ~in region~.  The newborn or neonatal litters in a female Feral Hog, averaging 4-6 piglets and can range from 1-12. Similar to the newborn litter size, the number of lactating teats per sow averages 4-6 and varies from 1-12. As such, the number of lactating teats is highly correlated with the number of piglets in the sow’s litter. The litter size in feral sows reportedly decreases after about the 5th-7th litter or 4-5 years of age. The oldest known feral sow, which was documented to still be capable of breeding, was 14 years of age.

Like the Wiley Coyote, they’re masters at making the most of their available resource by being omnivores to carnivores.

How To Control The Feral Hog Population

Property destruction left by Feral HogsNo single management technique alone can be totally effective at controlling feral pig populations ~in region~. Harvesting 66%-70% of the total population per year is required to keep the Texas feral pig populations stable. Best management practices suggest the use of corral traps which have the ability to capture the entire sounder of feral pigs

Predators such as bobcats and coyotes may occasionally take feral piglets or weakened animals, but are not large enough to challenge a full-grown boar that can grow to three times their weight. In Florida, feral pigs make up a significant portion of the panthers diet. This may be different ~in region~.  Because feral pigs are omnivorous, their feeding behavior disrupts the entire food-chain. Plants have difficulties regenerating from their wallowing as North American flora did not evolve to withstand the destruction caused by rooting pigs, unlike Europe or Asia. Feral pigs in the U.S. eat small animals such as wild turkey poults, toads, turtles and the eggs of reptiles and birds. This can deprive other wildlife that normally would prey upon these important food sources. In some case, other wildlife are out-competed by the feral pigs’ higher reproductive rate; a sow can become pregnant as early as six months old and give birth to multiple litters of piglets yearly. In the autumn, other animals such as the American black bear compete directly with feral pigs as both forage for tree mast (the fruit of forest trees).

Feral Hogs are now being hunted by farmers and ranchersIn the U.S. the problems caused by feral pigs are exacerbated by the small number of species which prey on them.  These large predators would include the gray wolf, cougar, jaguar, red wolf, black bear and the grizzly bear. Unfortunately, each keystone predator presents problems: the jaguar is extirpated from California and the Southwest. The grizzly, while native to most of the American West, is gone from the states that have large feral pig populations, namely Texas, Arizona, California and New Mexico; and the species has a very slow reproductive rate. Wolf numbers are small and expected to remain so as they slowly repopulate their range; only one has thus far been recorded as inhabiting California in spite of thousands of square miles of good habitat. The cougar is present in most of the West, but is gone from the East, with no known populations east of Minnesota in the north, and very thin numbers east of Houston in the South. The black bear is both predator and competitor. Programs do exist to protect the weakened numbers of large predators in the US, but it is expected to take a very long time for these animals to naturally repopulate former habitat

To control feral pig numbers in ~region~, American hunters have taken to trapping and/or killing as many individuals as they can. Some, in Texas, have even turned the trapping and killing of razorbacks into small businesses. Legal restrictions on methods of hunting are lax, as most state departments of wildlife openly acknowledge feral pigs as an ecological threat and some classify them as vermin. For example, in Wisconsin, the DNR considers them unprotected wild animals with no closed season or harvest limit, and promotes aggressive removal. (Most are viewing the FH in the Wisconsin manner)

Capturing Feral Hogs is another popular methodHunting with dogs is permitted and very common; it has been practiced in the Southeast for generations. Competitions for producing the fastest bay dogs are prevalent in the South, with Uncle Earl’s Hog Dog Trials in Louisiana a popular example, held every summer since 1995. Preferred scent dogs for catching feral pigs mostly are native breeds, and include the Louisiana Catahoula Leopard Dog, the Blue Lacy, all members of the Coonhound family, the Plott Hound, and the Blackmouth Cur; catch dogs typically are American Pit Bull Terriers and their crosses, and American Bulldogs. The method of hunting has little variation and usually the hunter will send out bay dogs trained to chase the pig until it tires and then corner it, then a bigger catch dog is sent out to catch and hold down the pig, which may get aggressive, until the hunter arrives to kill it.