The concept of stress and its relevance for animal behavior

Publisher Summary This chapter discusses the significance of the stress concept in gaining a better understanding of social mechanisms in nonhuman mammals. The development of this concept during the past years and the resulting present understanding of different stress reactions are described in the chapter. The triggers of stress reactions are mainly psychical processes resulting from the assessment of a situation by an individual. Dependent on the coping behavior of the individual, these processes lead to different physiological response patterns, which can result in a number of pathophysiological effects. The chapter introduces the most important currently applied methods in assessing stress levels in animals. Particular attention is paid to methodological problems, as well as to the limits of interpretation. The focal points of the chapter are the sympathetico–adrenomedullary and pituitary–adrenocortical systems, the pituitary–gonadal axis, and the immune system. An overview of the relationships between social situations and stress responses is provided, in which the research focuses on the monogamous and territorial tree shrews and the polygamous and territorial European wild rabbits. In these cases, the social rank of an individual, its sociopositive interactions with conspecifics, and the stability of the social system are determinants in the effects of a social situation on the individual's vitality and fertility.