There has been a dramatic shift in emphasis in studies of animal behavior during the development of the science of ethology. In recent years, there has been considerable emphasis in studies of animal behavior on systematically conducted field observations, or on controlled laboratory or field experiments, that generate quantitative data that can be analyzed statistically. Without this basis of knowledge about the fundamental aspects of behavioral biology in nature, much of our understanding and explanations of causation and function would be ungrounded. We must understand the environmental selective pressures that shape behavior to fully understand its functional significance. Classical ethologists distinguish between states of behavior and behavioral events .
Events often come in bouts , which are sessions of repetitive occurrences of the same event.
We may observe bouts of stepping or pecking while observing foraging Snowy Egrets. Deciding which events are to be included in a particular record of a bout is not always an easy task. Obviously these criteria are subjective, and depend on considerable knowledge of the natural history of the study animal in question. There are a number of sampling techniques used in the study of animal behavior. These range from very unstructured to very rigorously structured, and each has value in specific situations.