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-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
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For educational programming or technical assistance with wild pigs please contact:
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.
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).