In every branch of science, a careful and complete description of observed phenomena must precede experimental study. The study of behaviour is certainly no exception to this requirement.
When studying a species, however, achieving a comprehensive understanding of its behaviour is a challenging task. It requires patient observation and objective description of everything that constitutes its “behaviour,” since it has or may have an importance that must be carefully evaluated, especially in social contexts of communication. Such a study of the behaviour of a given species, prior to any other, is called an ethogram.
The ethogram is defined as a “behavioural catalogue” (Hennig 1906), or “the detailed catalog of all the behavioural modules of a species” (Eibl-Eibesfeldt 1995). Ethology itself began in the last century with the compilation of ethograms related to the species studied, including humans, with the identification and description of the morphological sequences of attitudes and movements that characterize their behaviour in all its expressions. As Nico Tinbergen points out, a study that also describes the muscles involved in the various movements and postures that constitute it would be ideal. Such a framework, however, is quite rare in ethological studies, and perhaps only Baerends and their colleagues (University of Groningen, Netherlands) have produced a (monumental) one for various species of Cichlid fish.
And so, as a young and hopeful aspiring ethologist, when I arrived at that institute, Gerard Baerends himself placed before me a stack of film recordings to help me understand the secrets of the life of one of those fish (Tilapia mariae), whose reproductive behaviour and associated color changes I was to study.
My task was clear: I had to learn to recognize those instinctive movements common to all individuals that characterized that species throughout its life cycle. I was to observe attitudes and postures, often fleeting but significant in social contexts, especially if they helped me understand its internal state and related appetites and dispositions. In other words, I had to complete its ethogram.
The figures accompanying this text represent, as examples, some of these postures and/or instinctive movements in different species. For felines, I relied on the masterful work of P. Leyhausen, “Il comportamento dei gatti” (The Behaviour of Cats” (Italian edition, Adelphi, Milan, 1994), as well as my own work on T. mariae (Monitore zoologico italiano 7: 247-290, 1973).
Why an Ethogram?
The importance of meticulous descriptive work on a species’ behaviour, as preparation for its experimental study, is essential to avoid misinterpretation or erroneous generalizations. Different species have their own ways of communicating, their own nonverbal “language”: knowing their ethogram allows us to understand it. As you can imagine, compiling such an inventory requires extensive observations in nature or in the laboratory, learning to distinguish between natural (instinctive and species-specific) behavioural expressions and those that are not, or those induced by life in confined environments (stereotyped movements typical of captivity). Bibliographic sources, photographs, film and television footage, and sonograms form the basis; however, the researcher’s work is in any case lengthy and challenging if they wish to achieve a result that enables accurate interpretation of the behaviour of experimental subjects, momentarily donning “King Solomon’s Ring.” Of great help to the researcher is the Institute for Scientific Film in Göttingen, which, since 1950, has collected a vast archive of technically flawless film and television footage of behavioural sequences from a wide variety of species.
In ethological terms, the ethogram is essentially an inventory of actions that Lorenz called “instincts”: innate elements specific to each species, also known as “fixed action patterns,” displayed in response to specific environmental or internal stimuli that trigger them.
Work on the ethogram led me to identify 34 of these action patterns belonging to territorial and non-territorial systems, or common to both. Subsequent experimental analysis allowed a description of the reproductive and agonistic systems of Tilapia mariae, including the nine different color patterns adopted in male/male and male/female interaction behaviours.
What is the value of the ethogram?
The ethogram is a study tool that follows the ethological logic of behaviour, where innate instinctual elements, typical of each species, play a crucial role in survival and adaptation to their habitat. These elements are the result of evolutionary processes that shape the species’ natural history. For those who believe behaviour is simply a chain of reflexes (reflexological theories) or the product of individual learning (behaviourist theories), studying an ethogram may seem meaningless. What value does it have if behaviour depends solely on an individual’s direct experiences (individual-specific behaviour) rather than representing the inherited traits of a species (species-specific behaviour)? However, as early as 1906, when Hennig recommended compiling a complete inventory of a species’ “action systems” before studying it, long before any definitive theory of behaviour genesis had been established, many already understood that behaviour is species-specific. Therefore, it is the “species” that must be understood in terms of its expressive features (nonverbal language) before its study. And he was right!
Credits
Author: N. Emilio Baldaccini Former Professor of Ethology and Conservation of Zoocenotic Resources at the University of Pisa. He has published over 300 scientific papers in national and international journals. Actively engaged in scientific education, he is also a co-author of academic textbooks on Ethology, General and Systematic Zoology, and Comparative Anatomy.
Translated by Maria Antonietta Sessa
