Network social dynamics of an ex-situ colony of African penguins following the introduction of unknown conspecifics

Zoos often alter social groups by moving individuals between collections to control numbers, maintain optimal genetic diversity, and for husbandry and management purposes. However, the impact of introducing new individuals into an existing social group is overlooked, and the consequences of these stressful events from an animal welfare perspective are underestimated. In this study, we use Social Network Analysis (SNA) to monitor and to investigate how the social dynamics of a colony of African penguins (Spheniscus demersus, n = 19) were affected by the introduction of groups of unfamiliar individuals (n = 6 and then n = 10) at different time intervals. The proximity data collected over a period of four months suggest that penguins established a non-random association and developed a significant level of preferred associations within the colony. Breeding pairs had a high degree of interaction with the rest of the colony, and their level of association was stable even when a new group was introduced. We found that the association preferences observed in the colony after introduction were not driven by sex and reproductive age. Instead, the main driver of association was the time of introduction, with individuals introduced at the same time being more likely to interact than those introduced at different times. We also speculate that, in addition to arrival time, familiarity plays a key role in group integration. In our specific case, the introduced penguins were already familiar with each other, having shared the same colony before arriving at the new one. Although the results are based on a case study and require further validation, they support the importance of maintaining relevant social ties within colonies and of relocating a few selected individuals who share prior familiarity to facilitate integration into a new colony. Our findings highlight the usefulness of implementing SNA to evaluate the impact of stressful events on the lives of animals.