ETD

• Crocuta crocuta
• ear posture
• relaxed open mouth
• social asymmetry
• social play
• visual cues

Social play offers a low-risk context in which animals practise motor and social skills while maintaining cooperation. In spotted hyenas ( Crocuta crocuta ), a species combining steep hierarchies with high social tolerance, play fighting closely resembles aggression yet remains non-hostile thanks to mutual inhibition and the use of clear visual cues. This thesis examines how intrinsic asymmetries (rank, kinship, sex, age) and visual expressive patterns shape the structure and modulation of play fighting.
Using 73 video-recorded sessions from the Ngorongoro Crater population, we quantified offensive and disadvantageous behaviours together with two visual features: ear posture and the Relaxed Open Mouth (ROM). Analyses showed that none of the tested intrinsic factors predicted the likelihood of using offensive versus disadvantageous patterns, nor the occurrence of short-term cooperation in polyadic play. This indicates that play structure does not simply mirror stable social or demographic differences between players, but instead arises from flexible, moment-to-moment interactional dynamics.
In contrast, ear posture varied with both behavioural context and rank distance: ears were held back more often during disadvantageous patterns and when players faced higher-ranking partners. ROM frequently co-occurred with ears-back but was unaffected by intrinsic traits, suggesting a highly flexible cue used to clarify playful intent. Overall, the results show that while stable asymmetries do not dictate how hyenas play, individuals rely on adaptable visual cues to manage transient vulnerabilities and maintain a cooperative, non-aggressive playful frame.