Texas has a pig problem, a problem that numbers in the millions. Russian wild boars, or feral hogs, are an invasive species in Texas. So, anyone with an interest in hunting can greatly help the state of Texas by participating in feral hog hunting. There are many benefits that come from helping to eradicate the wild boar invasive species.

Protecting Local Land

Feral hogs are a danger to themselves, other animals, and the environment. In short, they’re absolutely destructive, but you can help protect roads, crops, and animals when you participate in feral hog hunts. A study conducted by the Texas Department of Agriculture, reveals that these creatures cause roughly $52 million dollars in damage each year. Hunting these wild hogs keeps them from damaging the lands of local farmers.

Protect Local Animals

Feral hog hunting can protect local livestock from a host of diseases. Wild hogs are known to carry fleas, lice, ticks, and other parasites that can spread to other animals. Not to mention, since they’re an invasive species, they’re swarming all over the territories that belong to the native wildlife. This forces animals to compete with these invaders for food that would otherwise belong to them. In many cases, hogs even outright ruin the habits of other animals. When you join the fight against feral hogs, you’re protecting local livestock as well as native deer, turkeys, squirrels, and more.

Pork!

If you’re interested in helping your community in a unique way, book your feral pig helicopter hunting trip at Texas Helicopter Pig Hunting!

    Wild Pigs and Mast Crops

Wild pigs (Sus scrofa) are considered opportunistic omnivores – meaning they will consume both plant and animal food sources available to them throughout the year. The vast majority of a wild pigs diet consists of plant materials (Figure 1), and an important, seasonal food source for wild pigs are mast crops (acorns, fruits or beans). Common mast producing species in Texas include oaks, hickories, honey mesquite, prickly pear cactus and persimmon. This article will highlight the research that has been conducted on wild pig competition with native wildlife for mast, the effects mast has on wild pig population trends and how wild pigs’ consumption of mast can influence forest composition.

Figure 1. Wild pig diet composition6. *Other materials may include debris, garbage, lichen, rocks/gravel, soil/sand, etc.

Consumption of Mast and Competition with Wildlife

Mast crops represent a high-quality food source for wildlife and are consumed by many native Texas species including white-tailed deer, wild turkeys, collared peccaries and multiple small mammal species, including squirrels and rodents. Honey mesquite pods contain high concentrations of carbohydrates, some protein and several minerals, including sodium, calcium, iron, and zinc9. Acorns of both white and red-oak species (Figure 2) are high in fat and carbohydrates, and contain some vitamins and minerals, including calcium and phosphorus8, 15. Acorns of the red-oak group have a high concentration of phenolics and tannins15, which are compounds that can reduce palatability to wildlife.

Figure 2. Red Oak species vs. White Oak species. Red oaks generally have pointed tips on their leaves and white oaks generally have more rounded tips on their leaves. (Images Credit: Robert O’Brien, Texas A&M Forest Service)

Due to the variable environments and unpredictable levels of rainfall in Texas, mast crop production can vary widely between individual plants, species and years. For example, acorns from trees in the red-oak group are considered semi-annual producers since they take approximately 15 months (two growing seasons) to mature, whereas acorns in the white-oak group are considered annual producers since they only take approximately 3 months to mature (one growing season)12. These crops are often available in large quantities for limited periods of time, mainly in the fall and winter months. Because mast crops often are distributed unevenly across the landscape, there is potential for competition among various species of wildlife for these resources5.

To test this hypothesis, researchers at the Caesar Kleberg Wildlife Research Institute conducted an experiment to compare levels of mast intake between multiple native wildlife species (white-tailed deer, wild turkeys, collared peccaries, raccoons) and wild pigs by offering these various mast crops and measuring the rate of intake and total amount consumed by each species. Results of the study found that wild pigs can consume mast at an equal or higher rate than native species when consuming mesquite pods and live oak acorns, and had the capability of eating the relatively larger, astringent, red oak acorns that were rejected by raccoons and wild turkeys. The rates of intake and the ability of wild pigs to displace native wildlife species from feeding sites2 suggests that wild pigs can compete effectively with wildlife for mast crops5.

As stated above, wild pigs are opportunistic omnivores and are able to readily shift their diet between browse, mast and animal food sources throughout the year. Many native wildlife species, on the other hand, are very specialized in their diets and are unable to shift to new food sources when their usual ones run out. During productive years, this is generally not an issue, but in years where resources are scarce wild pigs can exhaust food supplies required by native wildlife, leaving these species with few options to survive.

Wild Pig Population Dynamics and Mast Intake

Mast crops are an important component in population dynamics of many species, including white-tailed deer, small mammals and wild pigs1, 11, 13, 18. The growth rate of wild pig populations has been shown to be correlated to the seasonal availability of mast producing tree species3, and the yield of both previous and current mast crops influences the timing of reproduction and the proportion of reproducing sows in a given year14.

A European research team conducted a long-term monitoring study of two populations of wild pigs, one on a 14,800 acre fenced preserve in Italy with low levels of mast crop production and low hunting pressure and the other on a 27,200 acre forest in France with high levels of mast crop production and high hunting pressure to assess how mast crops affect the reproductive output of sows7. Results of the study found that in both populations, abundant mast crop availability increased body mass, and reproduction. Abundant mast crop availability also led to direct increase in fertility, indicating that wild pig sows adjust their reproductive output to track resource availability7. Thus, sows born in years with high mast crop production should be heavier the next breeding season and potentially have higher fertility levels and larger litter sizes than sows born in years with low mast crop production7 (Figure 3).

Figure 3. Research showed increased fertility and litter size in wild pigs with access to abundant mast crops.

Acorns also contain the essential amino acid lysine, which is a primary determinant of milk production in domestic sows 19. Lysine concentrations in sow diets greatly influence offspring growth rates19. Therefore, litters born in a productive acorn crop year will have increased growth and future reproductive capability over litters born in unproductive years7.

Forest Dynamics

Wild pigs may impact the diversity of tree species found in forests through their consumption of mast crops and their destructive rooting behavior. Since seed number and seed size are generally negatively correlated10, mast producing species may be more sensitive to consumption by wild pigs simply because they are unable to produce as many seeds as small-seeded species such as grasses16. Rooting behavior can increase abundance of small-seeded and invasive species such as Chinese Tallow (Triadica sebifera) by creating favorable soil conditions and reducing competition from large-seeded species16.

In order to investigate this further, a study was conducted by researchers from Rice University and Texas A&M University over 7 years using exclusion plots in select areas of the Big Thicket National Preserve in Texas16. Results of the study found that mast producing species (hickory, oak, and tupelo) responded positively to wild pig exclusion and there was increased the diversity of woody plants in the forest understory, especially mast crop producing species, in exclusion plots versus non-exclusion plots16. In the non-exclusion plots, tree diversity was lower due to Chinese Tallow invasions, which were more than twice as abundant as in exclusion plots16. Increased wild pig management activities may be desirable in forests where mast producing species are the predominant part of the plant community and invasive plant species are present.

Conclusion

Overall, the relationship between native wildlife, wild pigs and mast crop species has been shown to be complex and incredibly interconnected. Wild pigs can effectively compete with native wildlife for these resources and exploit mast crops that many species find unpalatable, increasing their competitive advantage through increased fertility and reproduction. Exotic, invasive wild pigs also have the potential to change the species composition and diversity of forests through their consumption of mast crops, destruction of habitat and proliferation of invasive plant species. Continued wild pig control and damage abatement efforts remain imperative to keep both native wildlife and plant communities healthy and functioning.

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

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

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2 Berger, J. 1985. Interspecific interactions and dominance among wild Great Basin ungulates. Journal of Mammalogy 66:571–573.
3 Bieber, C. and Ruf, T. 2005. Population dynamics in wild boar Sus scrofa: ecology, elasticity of growth rate and implications for the management of pulsed resource consumers. Journal of Applied Ecology. 42: 1203-1213.
4 Elston, J.J. and Hewitt, D.G. 2010. Comparative digestion of food among wildlife in Texas: Implications for competition. The Southwestern Naturalist. 55: 67-77.
5 Elston, J.J. and Hewitt, D.G. 2010. Intake of mast by wildlife in Texas and the potential for competition with wild boars. The Southwestern Naturalist. 55:57-66.
6 eXtension. 2012. Food Habits of Feral Hogs. http://articles.extension.org/pages/63655/food-habits-of-feral-hogs.
7 Gamelon, M., Focardi, S., Baubet, E., Brandt, S., Franzetti, B., Ronchi, F., Venner, S., Saether, B. and Gaillard, J. 2017. Reproductive allocation in pulsed‑resource environments: a comparative study in two populations of wild boar. Oecologia. 183: 1065-1076.
8 Goodrum, P.D., Reid, V.H. and Boyd, C.E. 1971. Acorn yields, characteristics and management criteria of oaks for wildlife. Journal of Wildlife Management. 35: 520-532.
9 Harden, M.L., and Zolfaghari, R. 1988. Nutritive composition of green and ripe pods of honey mesquite (Prosopis glandulosa, Fabaceae). Economic Botany 42:522–532.
10 Leishman, M.R. 2001. Does the seed size/number trade-off model determine plant community structure? An assessment of the model mechanisms and their generality. Oikos 93: 294–302.
11 McShea, W.J., and Schwede, G.1993. Variable acorn crops: responses of white-tailed deer and other mast consumers. Journal of Mammalogy 74: 999–1006.
12 Pierce II, R.A., Dwyer, J., Stelzer, H. and Coggeshall, M. 2017. Managing Oaks for Acorn Production to Benefit Wildlife in Missouri.http://extension.missouri.edu/p/g9414.
13 Scarlett, T.L. 2004. Acorn production and winter reproduction in white-footed mice (Peromyscus leucopus) in a southern Piedmont forest. Southeastern Naturalist 3:483–494.
14 Servanty, S., Gaillard, J.M., Toïgo, C., Brandt, S., and Baubet, E. 2009. Pulsed resources and climate-induced variation in the reproductive traits of wild boar under high hunting pressure. Journal of Animal Ecology 78:1278–1290.
15 Short, H.L., and Epps Jr., E.A. 1976. Nutrient quality and digestibility of seeds and fruits from southern forests. Journal of Wildlife Management 40: 283–289
16 Siemann, E., Carillo, J.A., Gabler, C.A., Zipp, R. and Rogers, W.E. 2006. Experimental test of the impacts of feral hogs on forest dynamics and processes in the southeastern US. Forest Ecology and Management. 258: 546-553.
17 Timmons, J.B., Alldredge, B., Roger, W.E., and Cathey, J.C. 2012. Feral Hogs Negatively Affect Native Plant Communities. Texas AgriLife Extension. SP-467.
18 Wentworth, J.M., Johnson, A.S, Hale, P. E., and Kammermeyer, K.E. 1992. Relationships of acorn abundance and deer herd characteristics in the southern Appalachians. Southern Journal of Applied Forestry 16:5–8.
19 Yang, H., Pettigrew, J.E., Johnston, L.J., Shurson, G.C., and Walker, R.D. 2000. Lactational and subsequent reproductive responses of lactating sows to dietary lysine (protein) concentration. Journal of Animal Science 78:348–357.

Posted 20th December 2017 by Wildlife and Fisheries Extension
Labels: AgriLife Feral Hog forest dynamics habitat mast consumption population dynamics reproductionResearch resource competition Sus scrofa Wild Pig Wildlife wildlife mast foods