Perhaps because of their unusual social organization, gelada males have conspicuous traits that are good candidates for signals of fighting ability or quality. We are focusing on two of these candidates: a red patch of skin on the chest and neck, and a highly ritualized loud call used in male displays. We hypothesize that one or both of these traits are sexually selected signals that are used to assess future rivals or mates. Testing this hypothesis involves answering 3 questions: (1) Do these traits vary with status among males? (2) Do other geladas attend to these traits when assessing potential rivals or mates? (3) If so, are there costs associated with these signals to ensure that they remain “honest” indicators of quality? Thus far, our data suggest that male chest patches do vary with status, such that redder males are associated with greater reproductive opportunities (Bergman et al., 2009). We also have preliminary data to suggest that red chest patches are associated with at least two “costs” – high testosterone and high heat loss. We are conducting similar studies with respect to the male gelada loud call, which appears to be linked to male status and quality.

Our Relevant Publications

• Female reproductive ageing persists despite high infanticide risk in chacma baboons and geladas
• Assessing male gelada chest patches: color measurement and physiological mechanisms
• Social correlates of androgen levels and dispersal age in juvenile male geladas
• Beyond infant death: the hidden costs of male immigration in geladas
• Male-mediated prenatal loss: Functions and mechanisms
• Social and ecological drivers of reproductive seasonality in geladas
• Female reproductive parameters in wild geladas (theropithecus gelada)
• Is there an evolutionary trade-off between quality signaling and social recognition?
• Harem-holding males do not rise to the challenge: androgens respond to social but not to seasonal challenges in wild geladas