Vocalizations and accompanying behaviours of adult gelada baboons were studied in four one-male groups kept in large outdoor enclosures in the zoos of Stuttgart and Rheine. Twenty-two acoustically different vocal patterns were determined. According to behavioural context, they were grouped into two categories: (1) contact calls and (2) aggressive and defensive calls. Frequency of calling and the production of different vocalizations were related to social rank and to the age of the sender. Vocalizations in species of the closely related genera Papio and Macaca are compared and their evolution is discussed.

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