Affiliative Contact Calls during Group Travel: Chirp and Wail Vocalization Use in the Male Ring-Tailed Lemur (Lemur catta).

Affiliative vocalizations occur across primate taxa and may be used to maintain spatial cohesion and/or to regulate social interactions in group-living species. For gregarious strepsirhines like the ring-tailed lemur (Lemur catta), with large vocal repertoires and several distinct affiliative vocalizations including the chirp and wail, it is important to understand behavioural usage of these vocalizations to gain insight into their social interactions. To determine whether chirp and wail vocalizations facilitate group cohesion, regulate interactions to achieve socially positive outcomes, and are correlated with differences in individual characteristics such as dominance rank and age, I collected 565 h of focal data on 31 males aged ≥1 year at Beza Mahafaly Special Reserve, Madagascar, from March to July 2010. I found that chirp and wail vocalizations occurred at the highest rates during group-wide travel compared to other behaviours. Although nearest neighbour distance did not influence calling rate, focal animals maintained the same distance or were located closer to nearest neighbours after calling. Both chirp and wail calls were heard in behavioural contexts without agonism rather than agonistic contexts. No relationship was found between male calling rate and dominance rank or age, although the chirp showed a non-significant tendency to be produced at higher rates by younger males. Overall, my results indicated that ring-tailed lemur males of all ages and dominance ranks used both chirp and wail vocalizations as contact calls during group-wide travel events, helping individuals maintain proximity to other group members during movement. Chirp and wail vocalizations may additionally help regulate the caller's social interactions and promote increased tolerance from conspecifics. These findings add to our understanding of the breadth of communication behaviour in wild lemurs, thus furthering our knowledge of the social lives and cognitive abilities of strepsirhines. Through examining the complexity of vocalization use by a living lemur species with a communication system much like early social primates, we gain broad insight into the evolution of primate sociality.