Behavioural Development of Three Former Pet Chimpanzees a Decade after Arrival at the MONA Sanctuary

SIMPLE SUMMARY: Experiences during infancy and as a juvenile are very influential on the lives of primates into adulthood. In this sense, the living conditions of chimpanzees kept as pets or performing in circuses cannot fulfil the three basic requirements needed for these animals to develop properly: adequate functioning of the organism (physical well-being); an optimal emotional state with the absence of sensations such as fear, pain, grief or apathy (mental well-being); and the ability to express species-specific behaviours (social well-being). In this study, we compare the activity budgets of three chimpanzees approximately one-decade post-rescue, to historical activity data before their rehabilitation. We found changes in behavior patterns in accordance with the sanctuary rehabilitation objectives. All chimpanzees improved their social competence by adding new members to their social network. Vigilance behavior also declined, and time spent resting increased when living at the sanctuary. Our results support previous studies conducted with rehabilitated chimpanzees in sanctuaries and highlight the important work of dedicated professionals during the rehabilitation process for these chimpanzees housed in captivity for the rest of their life. ABSTRACT: Chimpanzees used as pets and in the entertainment industry endure detrimental living conditions from early infancy onwards. The preferred option for ending their existence as pet or circus chimpanzees is their rescue and transfer to a primate sanctuary that will provide them with optimal living and social conditions, so that they can thrive. In this case study, we had the rare opportunity to compare the activity budgets of three chimpanzees from their time as pets in 2004 to their time living at the MONA sanctuary in 2020, after almost a decade in the centre. We found their behaviour patterns changed in accordance with the sanctuaries’ rehabilitation objectives. Resting periods increased considerably while vigilance simultaneously declined sharply. Moreover, the chimpanzees’ social competence increased as allogrooming became the predominant social behaviour, and agonistic interactions diminished even though they were living within a larger social group at the sanctuary. All three chimpanzees expanded their allogrooming and proximity networks at the sanctuary, which included new group members, but they maintained the closest relationships to those conspecifics who they were rescued with. In conclusion, these findings suggest that the sanctuary environment and social group setting made it possible for these three chimpanzees to improve their social competence and increase their well-being over time.