ABSTRACT
All organisms express a full range of behaviours to interact with their environment. These behaviours have been classified into two main categories following the context in which they occur. The ‘everyday’ behaviours deal with any kind of ‘environmental necessities’ (i.e. feeding, drinking and moving), and the ‘display’ behaviours are involved in inter- and intra-specific communicative contexts (Lorenz, 1966). Since the early stages of ethology, research on the causal mechanisms that underlie the display behaviours and determination of these mechanisms have immediately posed general questions on the origin and phylogenetic changes of these display behaviours (Huntingford and Turner, 1987). Valuable information on the course of the evolution of these behaviours comes from descriptions of behavioural traits among members of a taxonomic group. This approach permits deduction of the behaviour of a hypothetical common ancestor and their origin (Huxley, 1966).
