Communication about predators through mental imagery in a wild bird (#362)
Mental imagery of external objects or events is fundamental to communication in humans, but its existence in other animal communication systems is controversial. Japanese great tits (Parus minor) produce two types of alarm calls for different predators, one specifically for snakes and the other for a wide range of predators. Using playbacks of these two alarm calls in concert with artificial ground movements, I tested whether tits associate ground movements with snake-specific alarm calls. I found that tits more readily approached the ground movements and inspected the surroundings when hearing snake-specific alarm calls. However, such a response to the artificial snake trace was not elicited by the playback of general alarm calls. In addition, the tits ignored the other movements of undergrowth that were not associated with snakes when receiving either snake-specific or general alarms. These results suggest that the tits retrieve mental imagery of a crawling snake when hearing snake-specific alarm calls. Therefore, the use of mental imagery for deriving information may be more widespread in animal communication than previously thought.