Colourful facial markings are associated with foraging rates and affiliative relationships in a wild group-living cichlid fish

Many animals use colour to signal their quality and/or behavioural motivations. Colourful signals have been well studied in the contexts of competition and mate choice, however, the role of these signals in non-sexual, affiliative relationships is not as well understood. Here, we used wild social groups of the cichlid fish Neolamprologus pulcher to investigate whether the size of a  brightly coloured facial patch was related to i) individual quality, ii) social dominance, and/or iii) affiliative relationships. Individuals with larger patches spent more time foraging and tended to perform more aggressive acts against conspecific territory intruders. We did not find any evidence that the size of these yellow patches was related to social rank or body size, but
dominant males tended to have larger patches than dominant females. Additionally, patch size had a rank-specific relationship with the number of affiliative interactions that individuals engaged in. Dominant males with large patches received fewer affiliative acts from their groupmates compared to dominant males with small patches. However, subordinates with large patches tended to receive more affiliative acts from their groupmates while performing fewer affiliative acts themselves. Taken together, our results suggest that patch size reflects interindividual variation in foraging effort in this cichlid fish and offer some of the first evidence that colourful signals may shape affiliative relationships within wild social groups.