THE STUDY OF ANIMAL COMMUNICATION HAS TRADITIONALLY FORMED AN important part of the study of animal behaviour. In recent years it has tended to become a sub-field in its own right, attracting workers of varied interests; it is also receiving increasing attention at the undergraduate level. Another recent development is an area which has come to be known as neuroethology. The problem for the neuroethologist is that much of behaviour is not reliable or "reflex-like" in its expression. Communicative behaviour, on the other hand, often is, and here neurophysiology can make a significant...