By the example of a signal behaviour of the tree crane species, an analysis of the logical grounds of the ritualization hypothesis has been performed. Its application to the origin and functioning of the "highly ritualized" communication signals in birds is discussed. It is shown that such signals are observed in a wide spectrum of situations, including those where a social partner for communication (perceiver) is absent. In the situations of its presence, a signal may be performed by a signaller in such a way that it cannot be perceived by the second bird. The same actions ("ritualized feather preening") vary in length and intensity, and such variability is present in practically all situations. In either of them, a hiatus between the ritualized preening, on the one hand, and those implementing a real comfort function is difficult to reveal. Such a state of things may take place even when a social partner is present. Short acts of preening, that may be readily considered as the ritualized signals, numerically predominate in all situations, including those where a partner is absent. The fact of the endogenous cyclic recurrence in the duets performance shows that communication cannot be regarded as exchange of signals in the mode "stimulus reaction-stimulus-reaction". The similar actions may look in the archaic species (the Siberian crane) as more ritualized than in evolutionary advanced one, such as the red-crowned crane. All these findings contradict the concept of emancipation and ritualization of the discrete behavioural acts in the process of evolution, as well as reality of the selection toward increase of the effectiveness of communication. The process, in accordance to the ritualization hypothesis, is transforming these actions into the special discrete signals that operate against the background of the "non-signal" everyday behaviour. A more realistic seems an understanding of communication as a process, in which an continued, unbroken behaviour of either communicant, taken as an entire united structure, is changing in the course of the mutual interactions a motivation statuses of a partner and, correspondingly, a line of its behaviour.
