Wild Boars Wash Their Food: Implications for Pig Ethology
Birds, raccoons, monkeys, and great apes have all been previously observed carrying food to water. However, not all have been shown to do so unambiguously – transporting food intentionally to a water source, and showing a distinction between items that do and do not need cleaning is rare. Pigs are intelligent animals capable of many learning and memory tasks; because of their intelligence, exhibiting food washing behavior would not be all that surprising.
In this study, a group of University College London researchers and Basel Zoo caretakers provided the first evidence of food washing in European wild boars (Sus scrofa). The findings were based on incidental observations and follow-up experiments at the zoo.
Through their observation, the researchers found that all adult boars and some juveniles carried apple halves soiled with sand to the edge of a creek where they put the fruits in the water and pushed them to and fro with their snouts before eating. Meanwhile, clean apple halves were never washed, indicating that pigs can discriminate between soiled and unsoiled foods.
It’s noted in the study that delaying gratification is a difficult skill, something that even highly intelligent organisms such as chimpanzees and human infants struggle with. The boars found apples less preferable than maize cobs or sugar beets. Maize and beets, whether clean or dirty, were consistently eaten without washing. This indicates that hunger or highly desirable foods could still override the need for washing foods.
Another factor influencing food washing could be competition – in a similar study, Carib grackles were less likely to dunk food in water when they had to compete for the resource. Furthermore, behavior of young piglets suggests that social learning might play a role in adopting food washing, just as when the young learn foraging techniques from adults.
Although the research does not ascertain the degree to which individual and social learning brings about food-washing behavior, animal advocates will definitely be able to use this information to highlight the impressive cognitive ability of pigs while advocating for awareness of their well-being. The fact that boars can learn to wash their food directly contradicts the common perception of pigs being filthy animals. Such a change in how we see them might aid when appealing to human compassion.