ABSTRACT
Behavioural ecologists are concerned with the evolution of behavioural strategies under the influence of natural selection. Of necessity, this must have involved modification of existing strategies or the development of new ones. In other words the evolution of behavioural strategies implies changes in the form of elementary activities and, qualitively and quantitatively, in the sequences in which they occur. This holds for activities with a direct instrumental function and, perhaps even more, for communicative behaviour.
