Comparison of the Social Structure and Behavior of All-Male and Family Groups in Captive Killer Whales

Abstract

The behavior of social animals is shaped by social structure, and individuals living in Family groups may differ from those in male-only groups. This study analyzed the social organization of different groups of killer whales (Orcinus orca) under captive conditions, and further examined short-term behavioral changes following the introduction of a new individual into an established group. The findings revealed differences in the social organizations of the family and male groups. In the male group, non-social behaviors accounted for 60.49 ± 2.91% of the overall behavior, significantly exceeding the 41.73% ± 1.93% observed in the Family group. The Male group also exhibited a lower social network density (0.466 vs. 0.525) and clustering coefficient (0.875 vs. 0.921) compared to the Family group, indicating weaker network cohesion. Notably, the Family group formed a social network centered on core individuals such as Katenka, while no similar key figures were identified in the Male group. The introduction of an adult male, Nakhod, into the Family Group was associated with increased non-social and sexual behaviors and reduced parent-child interactions. These findings contribute to our understanding of killer whale social organization and adaptation, with implications for the management of captive groups.