The reason for grouping together the chapters that appear in this part of the book is that each of them concerns communication behaviours that are best viewed from a communication network perspective, rather than from the more common dyadic (one signaller to one receiver) standpoint. It is a fact that, with the exception of choruses, most studies to date have implicitly or explicitly considered communication between a dyad. Although the communication network perspective of several signalling and receiving individuals seems to follow logically from what we know of natural communication, the dyadic viewpoint has historical precedence and considerable inertia. A network perspective will become more commonly adopted only if it is clearly better able to explain communication behaviours than a dyadic approach. It is for this reason that a network perspective has long been adopted in studies of choruses; the effect on an individual's signal timing of the signals of nearby conspecifics can be striking patterns, such as signal synchrony in the chorus (e.g. Greenfield, 2002; Ch. 13). Such patterns cannot be explained by considering communication as a dyad. All of the chapters in this book demonstrate the value of adopting a network perspective; however, it gives this demonstration more emphasis to begin with a section covering communication behaviours that are particularly suited to, or associated with, a network perspective.