Mental mapping abilities in domestic swine

Abstract

The presence of the mental mapping abilities, documented in animals such as chimpanzees, squirrels, and birds, was investigated in domestic pigs. Sixteen young, weanling, Landrace x Yorkshire crossbred pigs were selected and placed in two replicate groups for experimentation. Each of the two replications consisted of eight randomly selected animals. Each replication was divided into four test and four control animals. During tests, each test animal was independently transported around the test field and encouraged to watch while food items were hidden. The test animal was then returned to a holding area where it remained for a seven minute time period with the rest of the group members. Both control and test pigs from the replication were then released into the test field to search for the previously hidden food items. Two pigs were tested each day. This was repeated for a total of eight tests per test pig. Animals present during the distribution of the food items found significantly more hidden food items (144 of 194 items hidden, p < .001) than animals not observing the distribution of the food items (3 of 194 items hidden). Animals not present during the distribution of the 194 food items found only 3 of the hidden food caches. The test pigs demonstrated the ability to plan a goal directed path from the holding area location by deducing new paths of travel using the learned spatial relationships between different food drop locations and other environmental stimuli. These data suggest that pigs have the ability to form mental maps.