Group composition and friendship among olive baboons ( Papio anubis Lesson, 1827) in Kainji Lake National Park, Nigeria

Primate population studies have provided baseline data on the number of animals that can be monitored. Primate inventory is essential for the evaluation of population dynamics. However, there is no such regular inventory of olive baboons ( Papio anubis ) in Kainji Lake National Park (KLNP). This study centered on the group composition and interaction among groups of olive baboons in KLNP. Direct count method was used to determine the population structure of identified olive baboon groups. A group was identified in each of the four Ranges (Oli, Doro, Kali and Kemenji) where olive baboons were found distributed. Census was conducted in the morning (630-730hrs) and evening (1830-1930hrs) during the dry season for a period of three months (February - April). Analysis of variance (ANOVA) was used to determine the differences between the sampling periods, age groups and sampling locations. Linear regression analysis was used to determine the relationship between different age groups. There were 48 individuals in four olive baboon groups identified with adult male to female ratio of 1:2.13. There was no significant difference between the sampling periods. There was significant difference between the sampling locations. There was a positive demographic relationship (r 2 :0.25) between adult male and female olive baboons. Adult male and female olive baboons had close social interaction among each other. Olive baboons in KLNP had an optimum sex ratio. Adult male and female baboons cultivated friendships and were socially integrated. Observations and experimental studies on friendships between adult male and female should be conducted to substantiate the perceived benefits of social interaction in the study area. Keywords: friendship, group composition, Kainji Lake National Park, olive baboon