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.
KeywordsPigs Food washing Delayed gratification
- Fuster JM (2008) The prefrontal cortex, 4th edn. Academic Press/Elsevier, BostonGoogle Scholar
- Judge PG, Essler JL (2013) Capuchin monkeys exercise self-control by choosing token exchange over an immediate reward. Int J Comp Pyschol 26:256–266Google Scholar
- Laumer IB (2013) Delay of gratification in a food exchange task in Goffin cockatoos (Cacatua goffini). Dissertation, UniwienGoogle Scholar
- Lyall-Watson M (1963) A critical re-examination of food “washing” behaviour in the raccoon (Procyon lotor Linn.). J Zool 141:371–393Google Scholar
- Tomasello M, Call J (1997) Primate cognition. Oxford University Press, OxfordGoogle Scholar