Social significance of trunk use in captive Asian elephants

Tactile behaviour plays an important role in maintaining social relationships in several mammalian species. Touching with the tip of the trunk is a common social behaviour among Asian elephants (Elephas maximus). This is considered an affiliative behaviour; however, few studies have investigated it in detail. Therefore, this study aimed to determine whether this is an affiliative behaviour and whether it has other functions. We directly observed a group of captive female Asian elephants in Thailand. We found that the elephants usually touched each other with their trunks shaped in a U (U-type) or S (S-type) shape. The S-type shape was observed mainly when the elephants touched the lips of other elephants; however, this behaviour was occasionally observed in agonistic or play contexts, where it appeared to be a threat or dominant behaviour, particularly amongst adults. In contrast, the U-type shape was more frequently observed when the elephants were disturbed, where it appeared as a gesture for reassuranc...