Descriptive Analysis of the Social Network of South African Fur Seals (Arctocephalus pusillus pusillus) and California Sea Lions (Zalophus californianus) in Managed Care.

This study describes the social network of a captive group of six adult female and one adult male South African fur seals (Arctocephalus pusillus pusillus), observed on two days one month apart (23 December 2023 and 24 February 2024). Since the fur seals shared their enclosure with two adult male California sea lions (Zalophus californianus), a third observation (April 2024) focused on the mixed-species group. This resident otariid group was housed at the Faunia Madrid zoological facility in Madrid, Spain. A single observer recorded social behaviors using focal sampling with continuous recording for 65 minutes on 23 December, 70 minutes on 24 February, and 65 minutes on 24 April. Each fur seal was observed for a total of 200 minutes, while each sea lion was observed for 65 minutes. Additionally, three scans per session (pre-, mid-, post-observation) yielded 37, 42, and 39 scans, respectively, totaling 118 for fur seals and 39 for sea lions, allowing an assessment of space use in relation to access to valuable resources such as food. The results revealed stable interactive social networks for the most common affiliative behaviors (crossing swimming, rubbing, and synchronized swimming) in fur seals; no aggressive interactions were observed. Within the mixed-species group, two distinct subgroups emerged: one composed of the three oldest females and the adult offspring of two of them, and another consisting of the most recently introduced female along with the two male California sea lions. Sociograms generated allowed for the identification of both the most and least central individuals. Areas with greater resource availability were preferentially used by the animals compared to areas with fewer resources. Additionally, the animals that exhibited more frequency of use in the area with the greatest resource access were South African fur seals and California sea lions, and these animals also had the highest centrality values. [ABSTRACT FROM AUTHOR]