Skip to main content

Not eating like a pig: European wild boar wash their food


Carrying food to water and either dunking or manipulating it before consumption has been observed in various taxa including birds, racoons and primates. Some animals seem to be simply moistening their food. However, true washing aims to remove unpleasant surface substrates such as grit and sand and requires a distinction between items that do and do not need cleaning as well as deliberate transportation of food to a water source. We provide the first evidence for food washing in suids, based on an incidental observation with follow-up experiments on European wild boar (Sus scrofa) kept at Basel Zoo, Switzerland. Here, all adult pigs and some juveniles of a newly formed group carried apple halves soiled with sand to the edge of a creek running through their enclosure where they put the fruits in the water and pushed them to and fro with their snouts before eating. Clean apple halves were never washed. This indicates that pigs can discriminate between soiled and unsoiled foods and that they are able to delay gratification for long enough to transport and wash the items. However, we were unable to ascertain to which degree individual and/or social learning brought this behaviour about.

This is a preview of subscription content, access via your institution.


  • Allritz M, Tennie C, Call J (2013) Food washing behaviour and placer mining in captive great apes. Primates 54:361–370

    Article  PubMed  Google Scholar 

  • Fuster JM (2008) The prefrontal cortex, 4th edn. Academic Press/Elsevier, Boston

    Google Scholar 

  • Gieling ET, Nordquist RE, van der Staay FJ (2011) Assessing learning and memory in pigs. Anim Cogn 14:151–173

    Article  PubMed  PubMed Central  Google Scholar 

  • Judge PG, Essler JL (2013) Capuchin monkeys exercise self-control by choosing token exchange over an immediate reward. Int J Comp Pyschol 26:256–266

    Google Scholar 

  • Kawai M (1965) Newly-acquired pre-cultural behavior of the natural troop of Japanese monkeys on Koshima Islet. Primates 6:1–30

    Article  Google Scholar 

  • Kornum BR, Knudsen GM (2011) Cognitive testing of pigs (Sus scrofa) in translational biobehavioral research. Neurosci Biobehav Rev 35:437–451

    Article  PubMed  Google Scholar 

  • Laumer IB (2013) Delay of gratification in a food exchange task in Goffin cockatoos (Cacatua goffini). Dissertation, Uniwien

  • Leaper R, Massei G, Forman ML, Aspinall R (1999) The feasibility of reintroducing wild boar (Sus scrofa) to Scotland. Mammal Rev 29:239–258

    Article  Google Scholar 

  • Lyall-Watson M (1963) A critical re-examination of food “washing” behaviour in the raccoon (Procyon lotor Linn.). J Zool 141:371–393

    Google Scholar 

  • Mendl N, Held, Byrne RW (2010) Pig cognition. Curr Biol 20:R796–R798

    Article  PubMed  CAS  Google Scholar 

  • Morales M, Mundy P, Crowson M, Neal R, Delgado C (2005) Individual differences in infant attention skills, joint attention, and emotion regulation behavior. Int J Behav Dev 29:259–263

    Article  Google Scholar 

  • Morand-Ferron J, Lefbvre L, Reader SM, Sol D, Elvin S (2004) Dunking behaviour in Carib grackles. Anim Behav 68:1267–1274

    Article  Google Scholar 

  • Nakamichi M, Kato E, Kojima Y, Itoigawa N (1998) Carrying and washing of grass roots by free-ranging Japanese macaques at Katsuyama. Folia Primatol 69:35–40

    Article  PubMed  CAS  Google Scholar 

  • Oostindjer M, Bolhuis JE, Medl M, Held S (2011) Learning how to eat like a pig: effectiveness of mechanisms for vertical social learning in piglets. Anim Behav 82:503–511

    Article  Google Scholar 

  • Pacioni G (1986) Truffle hunting in Italy. Bull Br Mycol Soc 20:50–51

    Article  Google Scholar 

  • Perry S, Manson JH (2003) Traditions in monkeys. Evol Anthropol 12:71–81

    Article  Google Scholar 

  • Tomasello M, Call J (1997) Primate cognition. Oxford University Press, Oxford

    Google Scholar 

  • Visalberghi E, Fragaszy DM (1990) Food-washing behaviour in tufted capuchin monkeys, Cebus apella, and crabeating macaques, Macaca fascicularis. Anim Behav 40:829–836

    Article  Google Scholar 

  • Watanabe K (1994) Precultural behavior of Japanese macaques: longitudinal studies of the Koshima troops. In: Gardner RA, Gardner BT, Chiarelli B, Plooij FC (eds) The ethological roots of culture. Kluwer, Dordrecht, pp 81–91

    Chapter  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Volker Sommer.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sommer, V., Lowe, A. & Dietrich, T. Not eating like a pig: European wild boar wash their food. Anim Cogn 19, 245–249 (2016).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • Pigs
  • Food washing
  • Delayed gratification