Successful acquisition of an olfactory discrimination test by Asian elephants, Elephas maximus

The present study demonstrates that Asian elephants, Elephas maximus, can successfully be trained to cooperate in an olfactory discrimination test based on a food-rewarded two-alternative instrumental conditioning procedure. The animals learned the basic principle of the test within only 60 trials and readily mastered intramodal stimulus transfer tasks. Further, they were capable of distinguishing between structurally related odor stimuli and remembered the reward value of previously learned odor stimuli after 2, 4, 8, and 16 weeks of recess without any signs of forgetting. The precision and consistency of the elephants' performance in tests of odor discrimination ability and long-term odor memory demonstrate the suitability of this method for assessing olfactory function in this proboscid species. An across-species comparison of several measures of olfactory learning capabilities such as speed of initial task acquisition and ability to master intramodal stimulus transfer tasks shows that Asian elephants are at least as good in their performance as mice, rats, and dogs, and clearly superior to nonhuman primates and fur seals. The results support the notion that Asian elephants may use olfactory cues for social communication and food selection and that the sense of smell may play an important role in the control of their behavior.

► Asian elephants can successfully be trained in an olfactory discrimination test. ► The animals learned the basic principle of the test in only 60 trials. ► The animals readily mastered intramodal stimulus transfer tasks. ► The animals displayed excellent long-term odor memory. ► The animals' olfactory learning and memory performance is at least as good as that of dogs. ► Results support the notion that the sense of smell plays an important role for Asian elephants.