Social interactions that result in preferential relationships between individuals have been observed in multiple species of mammals. Female mammals tend to stay in long-term associations with other females, while males rarely maintain such interactions once they reach sexual maturity. For example, adolescent male giraffes (Giraffa camelopardalis) form bachelor herds in the wild and shift to a solitary lifestyle when they reach adulthood. Males in bachelor herds engage in social interactions and display preference and avoidance behaviors toward one another, indicating the establishment of individual-specific preferences. However, the process by which male giraffes’ transition from a social lifestyle as adolescences to a solitary existence as sexually mature adults is poorly understood. To understand this process, the frequency of social behavioral displays in a captive population of male giraffes at the Naples Zoo in southern Florida was examined as they transitioned from immature adolescence into adulthood. Younger male giraffes spent more time in close proximity to each other than did older males. While younger and older male giraffes showed similar frequencies of social behavioral displays, the types of behaviors that the males displayed changed with age. Younger males showed more contact interactions, such as neck bumping, while older males showed more sexual interactions and body examinations, such as mounting and anogenital exam. The amount of urine examinations remained constant, suggesting it was consistently observed throughout all ages. These results suggest that male giraffes change the type of social behavioral displays, consistent with their transition from a social to solitary lifestyle; older animals begin to separate and show agonistic behavioral patterns consistent with the formation of a dominance hierarchy and isolation.
