An Official Journal of ISPA, CRL and the Portuguese Ethological Society (SPE) The journal publishes research papers (both empirical and theoretical contributions), short communications, commentaries, reviews and book reviews as well as methods papers in the field of ethology and related disciplines, with a strong bearing on the behaviour of all animals, including humans. Special emphasis is placed on studies integrating proximate (i.e. mechanisms, development) and ultimate (i.e. function, evolution) levels in the analysis of behaviour. Aspects of particular interest include: - Adaptive plasticity of behaviour - Inter-individual and geographic variations in behaviour - Mechanisms underlying behaviour - Evolutionary processes and functions of behaviour - Comparative studies of behavioural traits - Behavioural development - Integrative approaches to the study of behaviour - Interspecific relationships, e.g. symbiosis, host-parasite relationships - Animal communication and social ethology Although descriptive ethological studies are also accepted, preference is given to experimental and field studies.