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.
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).
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.
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.
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, firstname.lastname@example.org
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).
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
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