Male-Male Greeting Behavior Observed in Chacma Baboons (Papio ursinus griseipes) in Gorongosa National Park, Mozambique.

OBJECTIVES: Male-male greetings have been described across many primate species, with varying forms and functions. Within Papio, their study has been of particular interest as baboons show variation in greeting, male-male cooperation, philopatry, and social systems. The function of greetings in Papio may differ by species, including facilitating cooperative behavior, negotiating rank, and maintaining social relationships. Chacma baboons, a species that generally exhibits limited to no coalition formation and low male-male tolerance, remain understudied regarding their male-male greeting behavior. MATERIALS AND METHODS: Here I present descriptions of male-male greeting behavior of chacma baboons (Papio ursinus griseipes) recorded in Gorongosa National Park, Mozambique in 2018 and 2019. Behavioral data was collected from video footage and categorized using established definitions from the published literature (e.g., presence and intensity of physical contact, reciprocity, and completeness). RESULTS AND DISCUSSION: Strong similarities in signal use between the sample of chacma baboon greetings and published accounts of olive, hamadryas, and yellow baboon greetings were identified. Specifically, rates of physical contact, intense physical contact, and reciprocal use of facial expressions were similar to those of the other Papio species, excluding the Guinea baboon which exhibits more stereotyped and highly physical greetings. The proportion of observed chacma baboon greetings which were considered "incomplete" (i.e., exhibiting only facial signals, with no presenting or contact) however, was greater than in the other baboon species, highlighting a key difference that may reflect the lower level of male tolerance and weaker male relationships in chacma baboons compared to other baboon species.