They are four-footed eating, breeding, rooting machines.
Feral hogs are an invasive species present in at least 35 states, according to the United States Department of Agriculture. They cause billions of dollars in crop damage each year, and their rooting causes widespread and lasting environmental damage, according to the USDA.
The porcine population bomb is exploding on farms and ranches, timberlands and suburban yards across the country. Sows become sexually mature at six months, and can drop two litters a year. The average litter size is six to 12 piglets. After reaching about two months old, the piglets have no natural predators. Adult hogs have no natural predators, other than man.
Hogs are omnivores, eating just about anything including plants, small animals and carrion.
Sam Upchurch, owner of Grey Rocks Ranch in Autauga County, talks about damage feral hogs inflict on the 5,700 acre ranch.Marty Roney/Advertiser
The problem
Grey Rocks Ranch is a sprawling spread of about 5,700 acres in western Autauga County. Sam Upchurch’s late parents built the ranch into a nationally recognized operation raising Santa Gertrudis cattle. Few cattle are raised here now. The ranch is now intensely managed for wildlife; deer, turkey and quail. The battle against the hogs is an ongoing and aggravating struggle, said Upchurch, an attorney who lives in Birmingham.
“If you don’t eliminate 70 to 80 percent of the population every year, you’re losing ground,” he said. “They are omnivores, they will eat just about anything. And the biggest thing is they destroy the habitat. And I am convinced that habitat is the most important thing for wildlife. Pigs destroy the habitat, they soil, the water and are generally just horrible animals.”
“If you don’t eliminate 70 to 80 percent of the population every year, you’re losing ground.”
SAM UPCHURCH, GREY ROCKS RANCHFor the past two years, the USDA has used helicopters to shoot hogs from the air at Gray Rocks. A gunner uses a semi-automatic 12 ga. shotgun to shoot the hogs. Over a four-day period last year, about 350 hogs we bagged. This year, the effort yielded 74 hogs.
Alabama is a hunting crazy state. Hunting generates an annual economic impact of about $1.8 billion a year in the Heart of Dixie, according to U.S. Department of Fish and Wildlife figures. Whitetail deer are ether most popular game animal in the state, according to the Alabama Department of Conservation and Natural Resources.
Hogs are present in all 67 counties in Alabama, according to the game department. A study conducted by Mississippi State University shows pig populations can double each year. Adult wild hogs eat 3 to 5 percent of their body weight daily, so, 100 hogs can eat 600 pounds of food daily or 110 tons each year.
The study shows there is about a 50 percent overlap in diet for hogs and whitetail deer in the fall, meaning hogs and deer compete for the same food sources. Hogs can live up to 10 years in the wild. When it comes to population control, the study shows that a 50 percent depredation of wild hogs is needed to stop population increases and a 70 percent removal of wild hogs yearly is needed if there is a chance to eventually exterminate the population.
Ty Baker, USDA employee, looks on as a USDA helicopter with a gunman flies over the tree-line during a  feral swine control program at the Grey Rocks Ranch in western Autauga County. (Photo: Albert Cesare/Advertiser)
But the complicating factor is hogs are a mobile scourge, said Mike Blake, ranch manager at Grey Rocks.
“They will move to where the food is,” he said. “So, if your neighbor has hogs, you’ll have hogs eventually. And if you have hogs, your neighbor will have hogs eventually.
“Somebody that has 20 acres out in the country, they are just as proud of their place as Sam is of this place. And hogs will do the same damage on 20 acres that we have seen here. You can’t stop trying to control them, it’s a year-round effort.”
 The MSU study shows that in 2012 in 41 counties in southwest Georgia, wild hog damage totaled $81 million. That breaks down to $57 million in agriculture and $24 million in non-agriculture damage. The damage ranges from row crop destruction to livestock mortality of newborn calves and young sheep and goats. Hogs also cost money in the timber industry, cutting production and impacting reforestation efforts. Then there are water quality issues, where fecal coliform levels increase and water quality decreases. And don’t forget infrastructure damage, the study points out, rooting causes problems in fields, roads and dams and levees.
Agriculture, which includes forestry, is the Number One industry in Alabama, according to the Alabama Farmer’s Federation. The industries drive a $70.4 billion annual economic impact and supply 580,295 jobs, federation figures show.
And don’t forget about the diseases wild hogs can carry. The Centers for Disease Control and Prevention show that feral hogs can carry 45 diseases and parasites that pose a risk to livestock, pets, wildlife — and in some cases — humans. For wildlife and livestock, those diseases include pseudorabies, swine brucellosis, bovine tuberculosis and leptospirosis. Hogs can also carry the foreign animal disease such as African Swine Fever, classical swine fever and foot and mouth disease.  
The MSU study shows that diseases wild pigs carry that can be transmitted to people include leptospirosis, swine brucellosis, e. coli, salmonellosis, toxoplasmosis, trichinosis, giardia and cryptosporidioses.
Clayton Glassey, USDA employee, aids Mike Blake, Grey Rocks Ranch manager, in loading a feral hog into his truck at the Grey Rocks Ranch in western Autauga County. (Photo: Albert Cesare/Advertiser)
The solution
Everyone generally agrees that the best way to control feral hogs is through trapping. Usually the traps are made of metal fence panels and have some type of door that can be tripped to trap the hogs. The most effective practice is to trap an entire group, or sounder, of hogs.
Alabama law forbids the transport of live feral hogs. Once the hogs are trapped, they have to be killed in the trap.
A point of contention among many landowners is the regulation that hogs can’t be hunted at night or over bait during deer season. Deer season runs from mid-October to Feb. 10 in the state. The game department’s logic is simple, the practice of shooting hogs at night and over bait could lead to more night hunting of deer, which is also illegal.
Everyone also generally agrees that controlling hogs isn’t possible one rifle bullet at a time. But still, every method should be used, Blake said.
“That’s a long time, from October to February,” he said. “We trap, hunt with dogs and shoot hogs. We should be able to hunt hogs year-round with little or no restrictions. If somebody is going to night hunt, they are going to night hunt. If your house is infested with roaches or mice, you get rid of them. And hogs are nothing but vermin.”
The no hunting at night over bait during deer season regulation will stand, said Chuck Sykes, director of the game department’s wildlife and freshwater fisheries division.
“Hunting hogs is a recreational activity, it is not an effective management tool,” he said. “Show me a credible study that says hunting is effective, and I’ll reconsider. But I’ve been doing this a long time, I’ve been there and done that. You can’t blow smoke up my skirt and convince me that hunting hogs is an effective tool.
“I’m protecting a $2 billion a year industry here. I’m not going to do anything that threatens the resource.”
“If your house is infested with roaches or mice, you get rid of them. And hogs are nothing but vermin.”
MIKE BLAKE, GREY ROCKS RANCH MANAGERThat approach is “short-sighted,” said Robert White, a Montgomery hunter. He hunts on family-owned land in Lowndes County. Hogs moved onto the place about three years ago.
“We don’t see the deer and turkey we used to see, after the hogs showed up,” he said. “And what really concerns me is we don’t have the deer and turkey on our game cameras like we used to. I’m no wildlife biologist, but I believe the hogs are the reason. If we don’t get a handle on these hogs, we may not have much of a deer population in a few years. The pigs are that big of a problem.”
Clayton Glassey, left, USDA employee, and Ty Baker, USDA employee, take blood samples and DNA from a hog shot from a helicopter during a USDA feral swine control program at the Grey Rocks Ranch in western Autauga County. (Photo: Albert Cesare / Advertiser)
Barry Estes and his brother, Bart, operate Alabama Hog Control Inc. The company sells and leases hog traps, but also takes paid hunters out for hog hunts at night. The two days after deer season ended this year, Barry Estes and clients hunting in Autauga County bagged 40 hogs while hunting at night.
“Hunting is not the most effective way, but it is a control method when you do it right,” Barry Estes said. “We shoot the big hogs, the sows and boars. That means the little hogs may get dumb and walk into those traps that the older hogs kept them out of. You may see those little hogs in the fields in daylight where you can get a shot at them.
“You need to be able to use every tool in the toolbox.”
Other states in the Hog Belt have different laws in dealing with hunting of feral hogs:

• Florida: On private land with landowner permission hogs can be trapped or hunted year-round. No hunting license is required and there is no bag limit. Both sexes may be harvested. A gun and light at night permit is not required to hunt wild hogs for using a gun and light on private land with the landowner’s permission.
• Mississippi: A hunting license is required for residents and non-residents. Landowners and leaseholders, and their designated agents, can hunt nuisance animals year-round at any time day or night. Bait is legal expect during spring turkey hunting season. Bait must be removed at least 10 days before hunting any game animals.
• Georgia: There is no limit and no closed season for feral hogs. Residents must have a valid hunting license unless they are hunting their own property. Non-resident must have a valid hunting license. Feral hogs may be hunted at night with a light which is carried on the person. Hunting over bait is allowed. There is no hunting from vehicles.
• California: A hunting license and wild pig tag are generally required. The season is open year-round and there is no bag limit.

The most effective trapping technique for feral hogs is to capture the whole sounder (family group) at one time, which requires that the pigs become acclimated to the trap and bait inside. 
(Photo: CONTRIBUTED )
A hunting license is required in Alabama for residents to hunt hogs. The exception is if they are hunting on land they own. Non-residents must get a hunting license to hunt hogs. License sales are key to the operation of the department, Sykes said. The wildlife and freshwater fisheries division receive no funding from the state budget. Money to run the division comes from federal taxes levied on the sale of guns and ammunition and hunting and fishing related equipment.
The state receives its portion of the federal money based on the sale of hunting and fishing licenses.
“If we didn’t require licenses to shoot hogs, how many hunting licenses do you think we would sell?” Sykes said. “Deer hunters would just sit on a pile of corn and say they were hog hunting. The only way our guys could build a case is if they saw the hunter dragging a deer out of the woods. And without license sales, we would have to close the doors.”
Back in Lowndes County, White is straight-forward about his hog control methods.
“We’ll trap, but we’ll also shoot every damn hog  get a chance to,” he said. “And we’ll pay the fine if it comes to that.”

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From left, Clayton Glassey, USDA employee, and Ty Baker, USDA employee, gather blood samples and DNA from a hog shot by the USDA from a helicopter as Mike Blake, Grey Rocks Ranch farm manager, ropes the hog.(Photo: Albert Cesare / Advertiser)
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Tourists looking for ever more thrilling holidays are taking to the skies above Texas to shoot wild hogs as part of the state’s effort to limit the spread of an invasive species that annually causes millions of dollars in damage to farmland and livestock nationally. 
For up to $50,000, people can hunt the feral hogs from a helicopter and even use a machine gun to mow them down. 
“There’s only so many places in the world you can shoot machine guns out of a helicopter and no one shoots back,” said Chris Britt, co-owner of HeliBacon, one of the companies offering the aerial hog hunts. 
SPONSORED

There were 2,752 helicopter hog hunts in Texas last year, up 81 percent from 2011, according to Texas Parks and Wildlife Department data. About 34,400 hogs were killed in those hunts, up 53 percent. 
The total U.S. population of the hogs is estimated at more than 6 million, and state and federal government officials are increasing efforts to rid themselves of the pesky animals. 
There are nearly 150 companies and individuals permitted to hunt invasive feral hogs from helicopters as part of the Texas’ so-called pork chopper bill passed in 2011. State legislators last month sent a bill to Governor Greg Abbott that would allow hog hunting from hot air balloons. 


Animals rights activists are not fans. 
“The Humane Society of the United States opposes the use of aerial gunning – whether from a helicopter or a hot air balloon – as a means of resolving conflicts with wildlife populations because it is unnecessarily cruel, dangerous and costly compared to other wild pig control methods,” said Samantha Hagio, a director at the agency. 
Slideshow (4 Images)However, aerial hunting is one of the most effective ways to eradicate hogs in open areas such as Texas fields of corn and rice that are destroyed, said Jack Mayer, manager of environmental sciences at Georgia’s Savannah River Laboratory and author of “Wild Pigs in the United States.” 
Even so, hunting and trapping are not keeping up with the rate of breeding and the feral herd continues to grow. 
“You are not even stemming the tide,” Mayer said by phone. 
Wild boars were brought to Texas and released for hunting in the 1930s. They bred with free-ranging domestic animals and escapees that had adapted to the wild, according to the Smithsonian. Since hogs, wild or otherwise, are not native to the United States, they have no predators and proliferated across Texas and other states. 
About $25.55 million was appropriated this year to the U.S. Department of Agriculture to tackle feral hogs on the national level and the agency is testing unmanned drones to track the hogs that thrive in swamps and forests, said Dale Nolte, the USDA’s feral swine program manager. 
Trump backs off emergency order to end shutdownHelicopter hunting already is allowed in Louisiana and Oklahoma legislators are considering a bill that would permit aerial hunts there. 
Hot air balloons could allow hunters to approach hogs more quietly than a helicopter or give shooters a steadier shot, Mayer said. 
In South Carolina, where aerial hog hunting is not permitted, farmer Rusty Kinard pays a local hunter $25 for each hog killed on his land. Still, there are hundreds near his fields and the hogs ate through nearly 30 acres (12 hectares) of peanuts last month. 
“We will kill them suckers, every one we can,” he said. 
Reporting by Michael Hirtzer in Chicago; Editing by Marguerita Choy

Our Standards:The Thomson Reuters Trust Principles.

The Texas House gave a final OK today to the "pork chopper" bill and sent it off to the governor's office. The bill would allow licensed hunters to hire helicopters and contract with landowners to shoot feral hogs and coyotes on their property from the sky. 
BY BRANDI GRISSOM AND BECCA AARONSON MAY 17, 20115 PM

REPUBLISH
James Stone's ranch outside of Lockhart on May 10, 2011. Hogs have hobbled Stone's property, ruining pasture land, killing trees and damaging fences. He estimates taking out over 500 hogs during the last three years.  Spencer SelvidgeThe Texas House gave a final OK today to the "pork chopper" bill and sent it off to the governor's office. The bill would allow licensed hunters to hire helicopters and contract with landowners to shoot feral hogs and coyotes on their property from the sky. The Senate approved the measure last week but changed the wording of the bill slightly to give the Texas Parks and Wildlife Department more authority to regulate who can pay for helicopter hunts. 
State Rep. Marc Veasey, D-Fort Worth, said feral hogs are becoming problematic even in urban areas like the one he represents, and asked whether feral hogs had any natural predators. 
Rep. Sid Miller, R-Stephenville, the author of bill, said no. "Man is the biggest predator, and I'm trying to increase that predation through this bill," Miller said. 
The bill passed with a vote of 141-1, and is now headed to Gov. Rick Perry's desk. The only vote against the measure came from Rep. Eddie Lucio III, D-Brownsville.

​By: Josh Helcel, Extension Associate
Texas A&M Natural Resources Institute

Wild pigs (Sus scrofa) are notorious for their ability to learn from past experiences and evade control efforts.  Groups of wild pigs that are not pressured often increase their diurnal activity and become more active during the day time (Gundlach 1967).  However, as abatement pressures increase wild pigs can alter their behavior to become more active at night and other behaviors can modify as well (Stegeman 1938, Hanson and Karstad 1959, Choquenot et al. 1996, Waithman 2001, Pei 2006).  This article will discuss various effects abatement techniques can have on wild pigs, and will recommend strategies that can help to minimize behaviors including trap aversion and escape when enacting control efforts for wild pigs.

Hunting Can Accelerate Wild Pig Birth Rates
It is accepted that sport hunting wild pigs alone will not significantly reduce populations.  Perhaps less apparent is that human activities such as hunting can influence evolutionary characteristics at both the population and species level (Darimont et al. 2009).  A good example of this has been observed in deer species (Odocoileus sp.); whereas high rates of trophy harvest were shown to lead to smaller overall horn size and body mass over time (Coltman et al. 2003).  In wild pig populations, however, high hunting pressure doesn’t necessarily lead to reduced body sizes or smaller tusks.  Extensive monitoring of wild pig populations over 22 years found that high hunting pressure can actually cause wild pigs to shorten their gestation period by as much as 12 days per cycle (Gamelon et al. 2011).  This acceleration is further compounded by increased conception rates of sows within their first year of life when populations are subjected to intense hunting or other abatement pressures (Gamelon et al. 2011).  Essentially, wild pigs may breed earlier and produce offspring more quickly when subjected to hunting pressure.  Given this novel survival strategy, it becomes more understandable why a state like Missouri banned completely the sport hunting of wild pigs on conservation lands.

 

Research indicated that wild pig sows subjected to high hunting pressure had higher conception rates in their first year and produced offspring up to 12 days sooner than normal gestation.
Wild Pig Adaptations to Aerial Gunning
Aerial gunning is an effective population reduction strategy unless limited by topography or dense canopy cover (Campbell et al. 2010).  However, previous research has shown that wild pigs can intelligently adapt their behavior to avoid detection and flushing by helicopters (Saunders and Bryant 1988).  It might be assumed that these animals would simply disperse from their home range in response to aerial gunning efforts.  In fact, research indicated the opposite in that core area and home range sizes did not alter either before or after enacting aerial control (Campbell et al. 2010).  Rather, wild pigs can adapt to aerial gunning by seeking dense cover and refusing to flush from it despite concerted efforts by the pilot and crew.  



Instead of flushing, some wild pigs have adapted to evade helicopters by holding within dense cover. 
 
What is significant about this behavior is that until relatively recently wild pig populations had not encountered significant predation from above their line of sight.  Despite this, they have quickly adapted to be capable of intelligently evading a formidable 5000 pound “aerial predator” that otherwise would seem to have every advantage.  The intelligence and adaptability of wild pigs are key factors that compound effective control (Sweeney et al. 2003), and this is again evidenced by their potential to evade aerial gunning efforts.

Trap Aversion
Research has long documented trapping as an effective population reduction technique, with 70-80% reductions in populations having been reported using this technique alone (Saunders et al. 1990, Vernes et al. 1999).  However, wild pigs can adapt to avoid traps altogether for a variety of reasons.  This can occur due to the size and type of trap used, but also can be attributed to inadvertently “educating” wild pigs through incomplete captures.  With the exception of solitary adult males (boars), wild pigs travel in social groups called sounders.  When trapping these animals, it is important to target and remove the entire sounder in a single trapping effort.  This is generally accomplished through a process of pre-baiting and conditioning the group over time to routinely enter a trap large enough to contain the entire sounder.  Corral style traps are often best suited for this, and research indicated this type of trap to be four times more effective than conventional box traps (Williams et al. 2010).  Box traps, while valued for their portability, usually only capture 1-3 animals at a time.  No matter what type of trap is used, incomplete captures can divide sounders and cause remaining pigs to avoid traps in the future. 


In order to minimize learned trap aversion due to incomplete captures, the goal of any trapping effort should be to target and remove the entire sounder of wild pigs.
Trap Escape
Wild pigs can also adapt to escape traps, and individuals that learn to do so often exhibit this behavior repeatedly.  Trap escapes can be accomplished through climbing, rooting, exploiting trap design flaws and even jumping considerable heights in excess of 4 feet.  It is important to construct and implement sound trap designs, and it is equally important to check traps as soon as possible following each trap night.  Many experienced trappers check their traps at first light and bring a firearm in order to harvest any residual pigs that may be near the trap site due to incomplete capture or escape.  The Texas A&M Natural Resources Institute recommends that corral traps be constructed with four to six 16’ cattle panels that have 5’ panel height and 4” mesh in order to minimize trap escapes.  It is generally not necessary to bury or trench paneling underground, but it is important not to leave any gaps at ground level or near the head gate.  Game cameras can be integral in monitoring wild pig activity at trap sites, and can also help to identify any modifications necessary in order to minimize the potential for trap escape.



Wild pigs will attempt to escape traps if given the opportunity. Ensure that traps are constructed properly and check traps at first light to help minimize trap escape attempts. (Image Credit: Andy James)

Conclusion
Wild pigs exhibit a variety of behavioral responses to abatement pressure.  Their intelligence and adaptability can complicate effective control, factors that are only compounded by their extreme fecundity.  It is important to select appropriate strategies as well as to adapt control techniques as necessary in order to minimize any potential issues which can reduce the success of abatement efforts.  This can undoubtedly be easier said than done, as is evidenced by the numerous and often remarkable ways in which wild pigs can evade control efforts despite the best technologies available to man.  However, best management practices including trapping, aerial gunning, strategic shooting, snaring, and the use of trained dogs remain proven tools that, when implemented in a combined approach, can successfully abate the damages associated with wild pigs.
 
Wild Pig Resources Listed Below are Available at the AgriLife Bookstore
 
– L-5523 Recognizing Feral Hog Sign– L-5524 Corral Traps for Capturing Feral Hogs
– L-5525 Box Traps for Capturing Feral Hogs
– L-5526 Placing and Baiting Feral Hog Traps
– L-5527 Door Modifications for Feral Hog Traps
– L-5528 Snaring Feral Hog
– L-5529 Making a Feral Hog Snare
– SP-419 Feral Hogs Impact Ground-nesting Birds
– SP-420 Feral Hog Laws and Regulations
– SP-421 Feral Hogs and Disease Concerns
– SP-422 Feral Hogs and Water Quality in Plum Creek
– SP-423 Feral Hog Transportation Regulations
– L-5533 Using Fences to Exclude Feral Hogs from Wildlife Feeding Stations
– WF-030 Reducing Non-target Species Interference While Trapping Wild Pigs
– ENRI-005 Wild Pigs Negatively Impact Water Quality: Implications for Land and Watershed Management
 
Click here for additional resources on wild pigs
 
_______________________________________________________________________________________


For educational programming or technical assistance with wild pigs please contact:
Josh Helcel, 512-554-3785, josh.helcel@tamu.edu
  
Literature Cited
Campbell, T.A., D.B. Long and B.R. Leland. 2010. Feral swine behavior relative to aerial gunning in southern Texas. Journal of Wildlife Management 74(2):337-341.
Coltman, D. W., P. O'Donoghue, J. T. Jorgenson, J. T. Hogg, C. Strobeck, and M. Festa-Bianchet. 2003. Undesirable evolutionary consequences of trophy hunting. Nature 426:655-658.
Choquenot, D., J. McIlroy, and T. Korn. 1996. Managing vertebrate pests: Feral pigs. Bureau of Rural Sciences, Australian Government Publishing Service, Canberra, Australia.
Darimont, C. T., S. M. Carlson, M. T. Kinnison, P. C. Paquet, T. E. Reimchen, and C. C. Wilmers. 2009. Human predators outpace other agents of trait change in the wild. Proc. Natl. Acad. Sci. USA 106:952-954.
Gamelon, M., A. Besnard, J. Gaillard, S. Servanty, E. Baubet, S. Brandt and O. Glmenez. 2011. High hunting pressure selects for earlier birth date: wild boar as a case study. Evolution 65(11):3100-3112.
Gundlach, H. 1968. Brutfursorge, Brutpflege Verhaltensontogenese und Tagesperiodik beim Europaischen Wildschwein (Sus scrofa L.). Zeitschrift fur Tierpsychologie, 25(8):955-995.
Hanson, R. P., and L. Karstad. 1959. Feral swine in the southeastern United States. Journal of Wildlife Management 23(1):64-74.
Pei, K. J. C. 2006. Present status of the Formosan wild boar (Sus scrofa taivanus) in the Kenting National Park, southern Taiwan. Suiform Soundings 6(1):9-10.
Saunders, G., and H. Bryant. 1988. The evaluation of feral pig eradication program during simulated exotic disease outbreak. Australian Wildlife Research 15:73-81.
Saunders, G., B. Kay, and R. Parker. 1990. Evaluation of a warfarin poisoning programme for feral pigs (Sus scrofa). Australian Wildlife Research 17(5):525-533.
Stegeman, L. J. 1938. The European wild boar in the Cherokee National Forest, Tennessee. Journal of Mammalogy 19(3):279-290.
Sweeney, J. R., J. M. Sweeney, and S. W. Sweeney. 2003. Feral hog. In ‘wild mammals of North America’. Johns Hopkins University Press: Baltimore, MD. pp. 1164–1179.
Vernes, K., C. N. Johnson and J. Mitchell. 1999. The effectiveness of trapping in reducing pig abundance in the Wet Tropics of north Queensland. In ‘Feral pigs: Pest status and prospects for control. Pp 51-56. Proceedings of a feral pig workshop. James Cook University, Cairns, March. Research Report No. 13. Cooperative Research Centre for Tropical Rainforest Ecology and Management, Cairns, Australia.
Waithman, J. 2001. Guide to hunting wild pigs in California. California Department of Fish and Game, Wildlife Programs Branch, Sacramento, California.
Williams, B. L., R. W. Holtfreter, S. S. Ditchkoff and J.B. Grand. 2010. Trap style influences wild pig behavior and trapping success. Journal ofWildlife Management 75(2):432–436.
 

Posted 30th May 2018 by Wildlife and Fisheries Extension
Labels: adaptability aerial gunning Box Trap Corral Trap Feral Hog head gate hog hunting intelligence reproduction Sus scrofa Trap Aversion Trap Avoidance Trap escape Wild Pigs
  

​By: Forrest Cobb, Research Assistant
Texas A&M Natural Resources Institute
 

 
  
Three years ago some of my colleagues and I spent every week checking and rechecking an electric fence we hoped would keep wild pigs out.  We were conducting a horticultural study with 1,600 fresh and tender ornamental plants grown over the course of a year.  Unfortunately for us, our small plot was not far from a creek that supported a seemingly endless population of wild pigs.  Every week we would see damaged brush, dead plants, and clumps of bare loose soil just outside the fence line.  Thankfully they never got inside, but while we had the luxury of fencing off and maintaining that relatively small enclosure, that same level of exclusion would not have been feasible for a larger tract of land and certainly is not for stream and rivers courses and their associated wetlands.  Impacts on agriculture, plant diversity, and wildlife habitat can be easily observed in areas disturbed by the rooting behavior of wild pigs.  One of their less obvious impacts, and the focus of our newest publication, is their impact on water quality in Texas.  But before we discuss some of these impacts, let's consider just how serious of an issue wild pigs have become.
 
Wild pigs now occur in at least 36 states and the economic toll of these animals in the US was estimated to exceed $1.5 billion in 2007, a number likely to be much larger today.  Population modeling indicates that as many as 3-5 million wild pigs now inhabit Texas and they are present in almost every county in the state (Figure 1).  The number and range of these animals is not surprising considering their incredible adaptability and fecundity.  With an average lifespan of 4-5 years, adult sows commonly produce litters of 4-6 offspring and can have 1-3 liters per year.  Their population growth is relatively unchecked by predators.  Coyotes, bobcats, and feral dogs have been known to prey upon juveniles but humans remain the only significant predators of adult wild pigs.  Population modeling has indicated that as much as 66% of the wild pig population would need to be harvested every year for 5 years or more to halt population growth.  With humans only harvesting an estimated 29% of the population per year, we will see continued growth and spread of wild pigs.  Omnivorous and intelligent, wild pigs are well adapted to conditions across the state and their foraging, opportunistic predation, rooting, and wallowing behaviors are incredibly disruptive, having serious repercussions for the ecological and economic health of our state.

 

Figure 1.  NMFSS data showing 2016 feral swine populations by county. (Image Credit – USDA-APHIS)
 
 
A worrisome aspect of wild pigs in Texas is the impact on water quality they have by damaging riparian areas and wetlands.  Since wild pigs lack sweat glands, they often stay close to water bodies in order to cool themselves by wallowing in wet, shaded areas. This concentrates wild pig populations in sensitive riparian areas, which are both crucial transitional zones between upland areas and water bodies, and a vital component of maintaining overall water quality.  Healthy riparian and wetland communities perform numerous critical functions which maintain water quality including, stabilizing soils, decreasing water velocities during flooding, providing fish and wildlife habitat, mitigating contamination from surrounding storm water runoff, and lowering water temperatures through shading.  Because of their disruptive rooting and wallowing behavior, as well as heavy foraging of native mast (fruits and nuts), wild pigs can significantly decrease native vegetation cover in riparian corridors.  By reducing native ground cover, native tree abundance, and native seedling establishment, they increase the presence and abundance of invasive plant species, and destabilize stream and river banks leading to increased sedimentation, nutrient loads, turbidity, and altered pH levels.
 
While they indirectly impact water quality through the destruction of riparian and wetland communities, wild pigs also directly impact water quality through defecation.  One study of fecal coliforms in the Buck Creek watershed of Texas found that as much as 50% of E.coli bacteria samples collected were from wildlife sources including wild pigs, while only 20% originated from domestic animals or livestock.  With a high defecation rate (1,121 grams per day) when compared to other wildlife species like white-tailed deer (500-772 grams per day), their contribution to bacterial loading and water quality is becoming a growing concern for land managers and regulatory authorities statewide.  Especially since, as of 2012, the majority of Texas water bodies were listed as bacterially impaired.  Bacterial impairment increases the potential for disease transmission in both wildlife and human populations.  Recreational activities such as swimming, wading, and fishing are necessarily restricted as a result of these unsanitary conditions.  
 
 

 Wild pig activity in and near water sources can spread invasive plant species, destabilize soil, reduce native species abundance, alter nutrient and pH levels, increase turbidity, and contribute to increased E. coli bacteria levels in surface water systems.
 
 
Agriculture is also impacted when access to high quality water becomes limited.  One study found that livestock with a quality water supply can produce as much as 20% more animal gain as compared to livestock with access to impaired water.  Furthermore, the low dissolved oxygen and high nutrient levels associated with impairment can reduce aquatic species abundance and diversity, and lead to massive algal blooms and fish kills. 
 
Wild pig populations contribute to impaired water quality in Texas, both directly through fecal deposition, and indirectly by altering wetland and riparian communities.  While more research is needed to quantify their impact and contribution to water impairment, wild pig abatement has been shown to benefit riparian ecosystems and overall water quality by reducing bacterial impairment, reducing the spread of invasive species, increasing vegetation cover, facilitating proper nutrient cycling, decreasing erosion, and decreasing surface water turbidity.  Given the wide spread and growing challenge posed by wild pigs in Texas, the potential benefits of management and control should be considered in any plan for improving or safeguarding water quality.  Application of consistent and widespread abatement efforts remains the only way of stabilizing and thus reducing the impacts of wild pig populations on landscapes and water quality in Texas.  
 
For more information on how wild pigs negatively impact water quality, please click the link below to download a free electronic copy of “Wild pigs negatively impact water quality: Implications for land and watershed management” from the AgriLife Bookstore.
  
http://www.agrilifebookstore.org/Wild-Pigs-Negatively-Impact-Water-Quality-p/enri-005.htm
  
Wild pig resources listed below are available at the AgriLife Bookstore
– L-5523 Recognizing Feral Hog Sign
– L-5524 Corral Traps for Capturing Feral Hogs
– L-5525 Box Traps for Capturing Feral Hogs
– L-5526 Placing and Baiting Feral Hog Traps
– L-5527 Door Modifications for Feral Hog Traps
– L-5528 Snaring Feral Hog
– L-5529 Making a Feral Hog Snare
– SP-419 Feral Hogs Impact Ground-nesting Birds
– SP-420 Feral Hog Laws and Regulations
– SP-421 Feral Hogs and Disease Concerns
– SP-422 Feral Hogs and Water Quality in Plum Creek
– SP-423 Feral Hog Transportation Regulations
– L-5533 Using Fences to Exclude Feral Hogs from Wildlife Feeding Stations
– WF-030 Reducing Non-target Species Interference While Trapping Wild Pigs
– WF-033 Wild Pigs and Ticks: Implications for Livestock Production, Human and Animal Health
– ENRI-005 Wild Pigs Negatively Impact Water Quality: Implications for Land and Watershed Management
 

Click here for additional resources on wild pigs

_______________________________________________________________________________________

For educational programming or technical assistance with wild pigs please contact:
Josh Helcel, 512-554-3785, josh.helcel@tamu.edu
 
References
Baird, J.V. 1990. Soil facts: Nitrogen management and water quality. North Carolina Cooperative Extension AG-439-2.
Campbell, T.A. and D.B. Long. 2009. Feral swine damage and damage management in forested ecosystems. Forest Ecology and Management 257:2319-2326.
Chavarria, P.M., R.R. Lopez, G. Browser, and N.J. Silvy. 2007. A landscape-level survey of feral hog impacts to natural resources of the Big Thicket National Preserve. Human Wildlife Conflicts 1:199-204.
Cushman, J.H., T.A. Tierney, and J.M. Hinds. 2004. Variable effects of feral pig disturbances on native and exotic plants in a California grassland. Ecological Applications 14:1746–1756.
Doupe´ R.G., J. Mitchell, M.J. Knott, A.M. Davis, and A.J. Lymbery. 2009. Efficacy of exclusion fencing to protect ephemeral floodplain lagoon habitats from feral pigs (Sus scrofa). Wetlands Ecology and Management. DOI 10.1007/s11273-009-9149-3
Gingerich, J.L. 1994. Florida’s Fabulous Mammals. World Publications. Tampa Bay.
Giovanni, G. D., L. Gregory, P. Dyer, and K. Wagner. 2007. Bacterial Monitoring for the Buck Creek Watershed – Final Report. Texas AgriLife Research, Texas Water Resources Institute, and Texas AgriLife Extension Service. TSSWCB Project 03-07.
Jay, M.T., Cooley, M., Carychao, D., Wiscomb, G.W., Sweitzer, R.A., Crawford-Miksza, L., Farrar, J.A., Lau, D.K., O’Connell, J., Millington, A., Asmundson, R.V., Atwill, E.R., and Mandrell, R.E. 2007. Escherichia coli O157:H7 in feral swine near spinach fields and cattle, central California coast. Emerging Infectious Diseases 13:1908–1911.
Kotanen, P.M. 1995. Responses of vegetation to a changing regime of disturbance: Effects of feral pigs in a California coastal prairie. Ecography 18:190-199.
Mapston, M. E. 2007. Feral hogs in Texas. AgriLife Extension B-6149 03-07, Texas A&M University, College Station, USA.
Naiman, R.J., H. Decamps, and M.E. McClain. 2005. Riparian: ecology, conservation and management of streamside communities. Elsevier, San Diego, USA.
Ohio State University Extension. 2006. Ohio livestock manure management guide. Bulletin 604. The Ohio State University, Columbus, USA.
Parker, I.D. 2010. The role of free-ranging mammals in the deposition of Escherichia coli into a Texas floodplain. Doctoral Dissertation. Texas A&M University, College Station, TX.
Pimental, D. 2007. Environmental and economic costs of vertebrate species invasions into the United States. Managing Vertebrate Invasive Species. College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
Siemann, E., J.A. Carrillo, C.A. Gabler, R. Zipp, and W.E. Rogers. 2009. Experimental test of the impacts of feral hogs on forest dynamics and processes in the southeastern US. Forest Ecology and Management 258:546-553.
Singer, F.J., W.T Swank, and E.E.C. Clebsch. 1984. Effects of wild pig rooting in a deciduous forest. Journal of Wildlife Management 48:464-473.
Taylor, R.B., E.C. Hellgren, T.M. Gabor, and L. Ilse. 1998. Reproduction of feral pigs in southern Texas. Journal of Mammalogy 79:1325–1331.
Texas Commission on Environmental Quality (TCEQ). 2013. 2012 Texas Integrated Report of Surface Water Quality for Clean Water Act Sections 305(b) and 303(d).
Timmons, J.B., J. Mellish, B. Higginbotham, J. Griffin, R. Lopez, A. Sumrall, K. Skow, and J.C. Cathey. 2012. Feral hog population growth, density and harvest in Texas. Texas A&M AgriLife Extension Service SP-472.
Williams, W.D., O. Kenzie, D. Quinton, and P. Wallis. 1996. The water source as a factor affecting livestock production. In: Animal Science research Development: Meeting Future challenges. Proceedings, Can. Soc. Anim. Sci., Lethbridge, AB. E

Posted 5th June 2018 by Wildlife and Fisheries Extension
Labels: aerial gunning bacterial source tracking Biology Distribution E. coli Feral Hogs Harvest Hunting Impaired watersPublication Riparian Sus scrofa Trapping water quality concerns Wetlands Wild Pigs
  

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Written by Shelby McCay, Texas A&M University, WFSC ’15 and MNRD ’19
Edited by Josh Helcel, Extension Associate, Texas A&M Natural Resources Institute

Wallowing is defined as coating the body surface with mud or a mud-like substance and while this behavior is not found exclusively in wild pigs (Sus scrofa) (rhinos, elephants, bovids and deer will also wallow) it is most commonly attributed to them (Bracke 2011). You may be wondering, why do they wallow?  What function does it serve?  As it turns out there are a variety of reasons why pigs wallow and we will explore each further here.
Thermoregulation
Both wild and domestic pigs are prone to overheating due to their lack of sweat glands and so they must use other methods to regulate their body temperature. These include moving during the cooler hours of the day, occupying shaded areas, or wallowing.  In Texas, wild pigs typically wallow during mid-day throughout the summer and into the early fall months in order to avoid the hottest parts of the day.  As average temperatures begin to decline, wallowing becomes less of a necessity for cooling and more of an opportunistic behavior.  So why do they use mud to cool off instead of just getting directly in water?  One study showed that it took two hours for the water in the mud on wild pigs to evaporate compared to only 15 minutes for just water (Ingram 1965).  Essentially, layers of mud can serve as a kind of long lasting “wet suit” to keep wild pigs cool in warm environments (Bracke 2011).

Health Benefits
In addition to aiding in thermoregulation, the mud layer wild pigs obtain from wallowing can provide multiple health benefits. Research has shown that mud can serve as a kind of protective layer against biting insects (Nalin 1996) and sunburn (Gegner 2001). One study found that wallowing could potentially help wild boars disinfect wounds caused by fighting through the bactericidal properties of the mud (Fernández-Llario 2005). Wild pigs can carry a variety of ectoparasites, including fleas, lice and ticks (Schuster 2011) and they usually carry the highest parasite load in the summer months (Bracke 2011).  Ticks in particular are commonly found behind the ears and on thin skinned areas where wild pigs have a hard time reaching (Bracke 2011) and are one of the most common ectoparasites found on wild pigs.  In a study conducted in Texas, seven different species of ticks were found on wild pigs across eight eco-regions (Sanders et al. 2013).  Wallowing can help wild pigs to remove some of these ectoparasites as the mud layer can trap some of them and the pigs can later remove by rubbing on either natural or manmade objects. Wild pigs will often intelligently seek out telephone poles and posts treated with creosote achieve this, as the compound is toxic to ectoparasites.  In areas with high wild pig activity, visible markings from their rubbing behavior can often be found. 


Wallowing and rubbing behavior helps to rid wild pigs of fleas, lice and ticks.

Sexual Function
In a 2005 study, Fernàndez-Llario looked at the wallowing behavior of wild boars in Spain and found that males wallowed mainly in the autumn months when temperatures and parasitic loads were low.  So if thermoregulation and parasite removal weren’t driving the wallowing behavior in the males, what was? To try to figure this out, the study also looked at the reproductive systems of sows and found that the primary breeding season stretched from the last part of October into the first part of November which overlapped with the increased wallowing behavior in the males. This suggests that there may also be a sexual function to wallowing for wild pigs, although further studies are needed to confirm this potential connection.


Research indicated that wallowing may also serve a role in wild pig reproduction. While more research is needed, adult males (boars) increased wallowing activity during active breeding periods.

Conclusion
Overall wallowing is unique behavior that serves many functions for wild pigs, but it does have negative environmental impacts on our Texas’s water systems.  Wallows can affect watersheds by muddying waters, creating bank erosion, creating algae blooms, destroying aquatic vegetation, and decreasing livestock use and fish production (Stevens 2010, eXtension 2012, Helcel et al. 2018).  Wild pigs will often create wallows in moist areas near ponds, creeks and sloughs since they offer easy access to mud and as they lie in these areas they will defecate, adding bacteria and pathogens into the water resulting in impairments to the system and degrading the ecosystem (Peterson et al. 2012, Helcel et al. 2018).  This fecal contamination can transmit pathogens that can threaten agricultural production, livestock productivity, wildlife, and limit human use (Helcel et al. 2018).  Consistent and widespread abatement efforts remain important in reducing the damages associated with wild pigs, and can lead to  improved water quality, habitat and overall ecosystem functionality. 
Wild pig resources listed below are available at the AgriLife Bookstore
– L-5523 Recognizing Feral Hog Sign
– L-5524 Corral Traps for Capturing Feral Hogs
– L-5525 Box Traps for Capturing Feral Hogs
– L-5526 Placing and Baiting Feral Hog Traps
– L-5527 Door Modifications for Feral Hog Traps
– L-5528 Snaring Feral Hog
– L-5529 Making a Feral Hog Snare
– SP-419 Feral Hogs Impact Ground-nesting Birds
– SP-420 Feral Hog Laws and Regulations
– SP-421 Feral Hogs and Disease Concerns
– SP-422 Feral Hogs and Water Quality in Plum Creek
– SP-423 Feral Hog Transportation Regulations
– L-5533 Using Fences to Exclude Feral Hogs from Wildlife Feeding Stations
– WF-030 Reducing Non-target Species Interference While Trapping Wild Pigs
– WF-033 Wild Pigs and Ticks: Implications for Livestock Production, Human and Animal Health
– ENRI-005 Wild Pigs Negatively Impact Water Quality: Implications for Land and Watershed Management


Click here for additional resources on wild pigs

______________________________________________________________________________________________

For educational programming or technical assistance with wild pigs please contact:
Josh Helcel, 512-554-3785, josh.helcel@tamu.edu


References
Bracke, M.B.M. 2011. Review of wallowing in pigs: Description of the behaviour and its motivational basis. Applied Animal Behavior Science 132, 1-13. 
eXtension. 2012. Feral Hog Behavior. http://articles.extension.org/pages/64381/feral-hog-behavior.
Fernández-Llario, P., 2005. The sexual function of wallowing in male wild boar (Sus scrofa). Journal of Ethology. 23, 9–14.
Ingram, D.L., 1965. Evaporative cooling in pig. Nature 207, 415–416.
Gegner, L., 2001. Considerations in organic hog production. ATTRA’s organic matters series. http://www.organicagcentre.ca/Docs/ ATTRA/hog production2001.pdf. 
Helcel, J., Teel, P., Tyson, M., Cash, J., Hensley, T., and Cathey, J.C. 2016. Wild Pigs and Ticks: Implications for Livestock Production, Human and Animal Health. AgriLife Extension Service. https://wildpigs.nri.tamu.edu/media/1293/ewf-033-widl-pigs-and-ticks-implications-for-livestock-production-human-and-animal-health.pdf.
Helcel, J., Cobb, F. and Cathey, J. 2018. Wild pigs negatively impact water quality: Implications for land and watershed management. AgriLife Extension Service. https://wildpigs.nri.tamu.edu/media/1187/enri-005-widl-pigs-negatively-impact-water-quality-implications-for-land-and-watershed-management.pdf.
Nalin, D.R., 1996. O come, let us wallow in glorious mud’ Transactions of the Royal Society of Tropical Medicine and Hygiene, 90, p. 717.
Peterson, J., Cathey, J., Wagner, K. and Redmon, L. Lone Star Healthy Streams Feral Hog Manual. Texas A&M AgriLife Extension. http://www.agrilifebookstore.org/Lone-Star-Healthy-Streams-Feral-Hog-Manual-p/esc-005.htm.
Sanders, D.M., A.L. Schuster, P. W. McCardle, O. F. Strey, T. L. Blankenship, and P. D. Teel. 2013. Ixodid ticks associated with feral swine in Texas. Journal of Vector Ecology. 38:361–373.
Stevens, R.  2010.  The feral hog in Oklahoma. The Samuels Roberts Noble Foundation, Ardmore, Oklahoma, USA.  
Schuster, A.L. 2011. Spatial and Temporal Survey of Feral Pig Ectoparasites in Three Texas Wildlife Districts (Doctoral Dissertation). 
http://oaktrust.library.tamu.edu/bitstream/handle/1969.1/ETD-TAMU-2011-12-10290/SCHUSTER-DISSERTATION.pdf;sequence=2. 


Posted 28th September 2018 by Josh Helcel
Labels: A&M adaptability AgriLife bacteria cooling Feral Hogs fleas impairment lice reproduction Riparian rub Sus scrofa tamu thermoregulation Ticks wallowing water quality Wild Pigs