Lack of effects of environmental changes on agonistic behaviour patterns in a stabilizing group of stumptailed macaques (Macaca arctoides)

To evaluate how constant the form of agonistic interactions in the event of environmental changes is, a group of 11 stumptailed macaques, formed shortly before the start of the study, was observed under the following spatial conditions: in 10 and 18 m² cages, and in a 50,000 m² woodland. Results showed that the frequency of agonistic interactions was little affected by spatial density; however, the number of participants involved in aggressive interactions increased in the cage. Formal biting, which presumably acts as a regulator of social tension, was less frequent in the park. Patterning of agonistic interactions was little affected by spatial density. Such “robustness” makes the form of aggression liable to be used as a potentially useful parameter in interspecific comparisons.