Watching Stump-Tailed Macaques
This video record has been made of an ongoing behavioral study which is being carried out by the Department of Endocrinology, Growth and Reproduction at Erasmus University, Rotterdam. The film deals with the methods used and how observations were made. It shows how the animals interact aggressively, socially and sexually. It also shows how behavioral information can be expressed in measures and figures presented in the form of tables and graphs.
THE OBSERVATIONS revealed clear-cut linear dominance hierarchy among both males and female. Around puberty (three years of age) daughters acquire a rank directly below their mother and retaine this rank in adulthood. Pubertal males challenge older males, which enables them to rise in the hierarchy from the low to sub-positions. In the wild, young males usually leave their native group.
THE TOP-RANKING MALE was involved in almost 50% of the copulations. He and other high-ranking males copulate with females of all ages, while middle-ranking males copulate exclusively with young adult females. The three lowest ranking adult males did not copulate at all. The two highest-ranking females copulate almost exclusively with top=ranking males.
THE HORMONAL DATA made it impossible to determine retrospectively when females had ovulated and when they had become pregnant. No significant relationships were found between this hormonal data and behavioral data. In males, sex hormones did not appear to influence any aspect of behavior.