Invasion of the Hogs

Invasion of the Hogs
Feral hogs continue to expand their range—and as they do, bird hunters had better brace for the invasion and become part of the conversation about how to manage them. Photograph by Lori Thomas.

 Human travel has made the biological world a smaller place—a transformation that has brought us a host of invasive, destructive species ranging from nutria to knapweed. In contrast to these relatively new arrivals, the one under discussion here arrived on our shores five centuries ago, when Spanish explorer Hernando de Soto released Old World swine in what is now Florida. Thanks for nothing, Hernando.

Colonists subsequently imported domestic swine, which often escaped captivity and interbred with feral stocks. Hunters then compounded the problem by introducing Eurasian boars for sporting purposes from New England to California. They, too, escaped confinement and contributed their genes to the feral population. All Old World swine are members of the same species, Sus scrofa, whichincludes barnyard pigs, “razorbacks” and “Russian boars.” Being conspecific, all can interbreed. Importing them may have seemed like a good idea at the time, but the final result was an expanding population of large, potentially dangerous, omnivorous wild mammals capable of eating almost anything—including the gamebirds we hunt and their eggs.

Feral hogs’ destruction of crops and wild native habitat has been widely documented, their impact on gamebirds less so. But as feral swine continue to expand their range, bird hunters living in previously hog-free areas had better brace for the invasion and become part of the conversation about how to manage them—to the extent that they can be managed at all.

Texas has more feral hogs than any other state—recent estimates put the population as high as 2.6 million—and a lot of the research on hogs has been conducted there. Biologists became particularly interested in the temporal association between exploding hog numbers and dramatic declines in Texas quail populations.

A study from Texas A&M noted “evidence both circumstantial and direct that feral hogs can be detrimental to quail.” Field studies showed that feral hogs were responsible for 10 to 30 percent of quail nest destruction. This isn’t surprising, given that other predators that eat ground-nesting-bird eggs, such as raccoons and skunks, depend on their keen sense of smell to locate nests, and hogs have some of the best snouts of all mammals. Studies with collared hogs also have shown that they develop “search images” targeting quail, shifting their feeding behavior seasonally toward areas and habitats favored by nesting gamebirds. This behavior makes them even more efficient predators on quail and wild turkeys. Hogs don’t just have good noses. They are among the most intelligent mammals on earth.

One Texas study concluded that feral hogs “are likely not the sole cause of (quail) decline, but their potential for negative impact is tangible and undeniable.” This opinion has become a consensus within the wildlife-biology community. A position statement from the US Department of Agriculture, which oversees the Forest Service, noted that: “Feral swine directly impact native game species by preying on the nests, eggs, and young of ground-nesting birds.”

As more and more states have started to face the growing hog problem, references to the animals’ adverse impacts on gamebirds have appeared in almost all of the arguments for some kind of proactive legislation.

Hogs aren’t bad for gamebirds simply because they eat their eggs and chicks either. They are incredibly destructive when they feed, and they can make bird habitat look as if it were hit by a rototiller overnight. They destroy a variety of native vegetation, some of which is important to gamebirds as food and security cover. They foul waterways by wallowing, and they carry diseases, including pseudorabies, and a number of parasites.

The effects of some of these pathogens on waterfowl remain largely unknown. However, a study in Louisiana documented higher concentrations than expected of leptospira, salmonella and E. coli in wild waterways frequented by hogs. Sophisticated DNA analysis linked these known pathogens to those found in stool samples from the local hog population. Even though these organisms rarely cause overt disease in waterfowl, ducks can act as vectors to spread them to other areas where they can cause serious illness in people and livestock.

One disturbing aspect of the feral-hog problem is the speed with which the animals are expanding their range. Until recently, they were a Southern problem. Now they have established self-sustaining populations in at least 35 states, and that number is growing. Because of their initial concentration in Southern climates, many of us who live farther north never imagined we’d see them. That’s wishful thinking. Swine are one of the most widely adapted large-mammal species in the world—second perhaps only to our own. In Eurasia they tolerate extreme cold well. Large numbers of hogs, presumably derived from game-farm escapees, are currently massing in Saskatchewan just across the border from my Montana home. No matter where in the country you live, it’s only a matter of time until you have feral hogs in your bird coverts.

Identifying the hog problem proves to be a lot easier than solving it. Hogs can thrive in almost any habitat and eat almost anything. As noted, they are uncannily smart and soon become nocturnal when faced with hunting pressure. They are prolific, with sows typically producing two litters of up to a dozen young per year. Wild hogs can neither be fenced in nor fenced out. It’s easy to conclude that this horse already has left the barn . . . and perhaps it has.

However, almost every state with an actual or potential hog problem is trying to do something about it even if these efforts suffer from a lack of science and an air of futility. The differences in the way various states are approaching the problem illustrates the difficulties ahead.

Texas has declared war on hogs by hunting. There are no closed seasons or limits, and no license is required. Hunters can shoot them at night, over bait and from the air. Despite all of this, the Texas hog population has continued to increase.

Montana has taken a diametrically opposed approach. Although there is no documented hog population in the state yet, wildlife managers are well aware of the problem looming just north of the border. They also recognize that many of the country’s isolated hog populations, likely including the one in Saskatchewan, originated from stock deliberately introduced by hunters for sporting purposes. Concluding that such importation will be the most likely route for wild hogs to enter the state, authorities have simply banned all hog hunting, reasoning that if you can’t hunt them, no one will bring them here.

Although I understand the reasoning behind the Montana policy, I can’t endorse it. Hunting hogs is one thing, but importing hogs to hunt is another. The latter is a major problem, but the former, even though it will never get rid of all the hogs, can only help—especially when a small number of them have escaped confinement or started to trickle into a new area. I’m for anything to keep them out of the local pheasant cover.

The specifics of these management issues may not be important to wingshooters in other regions now, but all of us will need to become informed and involved as our own states seek ways to limit expanding hog populations. At the very least, eliminating game-farm hog hunting and studying improved methods of confining domestic pigs seem like reasonable first steps.

Eliminating feral hogs completely is not a realistic goal, but we may be able to slow their expansion and limit their numbers. The birds we hunt will appreciate the effort.  

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1 Comment

  • Hunting (or shooting) hogs does nothing to eliminate or control the hog population. For every hog you shoot, a dozen others are taught to be more careful and avoid humans, etc. The way to eliminate hogs is with traps that capture the entire sounder. There are several companies that manufacture such traps or you can build your own with cattle panels and a deer feeder.

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