Coping with social conflict, and short-term changes of plasma cortisol titers in familiar and unfamiliar environments.

Each of 27 male guinea pigs was confronted with a strange opponent a) in its familiar home cage (CHC) and b) in the unfamiliar cage of the opponent (CSC) and was c) exposed to an unfamiliar open-field area without a conspecific present (OFA). The behavior displayed during confrontations was recorded in detail and plasma-cortisol-titers (PCT) were measured immediately before and after each test. The main findings were: 1) PCT increased significantly in response to the tests carried out in unfamiliar environments (OFA and CSC) compared with the response to the home-cage confrontation. 2) In both confrontation tests "offensive" males could be distinguished from "defensive" males according to marked differences in their agonistic behavior. Offensive males approached and threatened their opponents. Defensive males retreated and did not perform elements of threat behavior. 3) Offensive males showed significantly lower increases in PCT than defensive males in the home-cage confrontations. Increases in PCT did not differ significantly between the two categories of male in the strange-cage confrontations. The results show a) that different intensities of adrenocortical responses depend on the behavioral coping pattern and b) that this behavioral effect can be masked by environmental factors.