Not lost in translation: Changes in social dynamics in Bonobos after colony relocation and fusion with another group

Animal welfare is affected by both physical and social environment and these aspects can be particularly critical for cognitively and socially-complex species, such as great apes. We observed a captive group of nine bonobos before (April-June 2021) and after relocation (June-August 2022) and we checked whether and to what extent the transfer would affect their social behavior after a stabilization period. The group was transferred from La Vallée des Singes (Romagne, France) to Ouwehands Dierenpark (Rhenen, the Netherlands), where it was merged with the resident bonobo group (N = 4). The two zoological parks had outdoor and indoor facilities that were similar in both size and enrichment quality/quantity. We focused on four behavioral categories: conflict, affiliation (i.e., grooming and sit-in-contact), social play, and socio-sexuality. Via non-parametric tests and social network analyses we investigated whether the frequencies of these behaviors – involving adults and immature subjects - differed: i) within the relocated group members before and after transfer; and ii) between relocated and resident group members. The transfer did not affect conflict rates within the relocated group and mainly involved inter-group interactions. Nevertheless, the relocated group hierarchical and agonistic networks changed after relocation. Affiliation via grooming and sit-in-contact was higher after relocation and between relocated group members. There was a reorganization of the affiliative social network, possibly to strengthen pre-existing social relationships. Compared to the pre-relocation period, after relocation social play was higher and involved a larger network, particularly involving immature subjects. Hence, social play was probably used by young individuals to enhance new relationships. Adult socio-sexual behaviors were higher before than after relocation and between groups, resulting in a reorganization of the social network for this behavioral category. Socio-sexual behaviors were probably used to enhance new relationships, especially between adults. Overall, via the follow-up before and after relocation/merging, our study was able to highlight that different affinitive patterns – all used to ‘friendly’ relate to others – may have served (at least in part) different functions in the adaptation process. Bonobos adapted their behavior to maintain pre-existing relationships (through grooming) and establish new relationships (through social play in immatures and