Behavioral Endocrinology of Male Dispersal in Vervet Monkeys at Lake Nabugabo, Uganda

Dispersal between social groups reduces risks of inbreeding and may provide individuals with reproductive opportunities. However, this movement may come with socio-ecological costs, such as risks of predation and starvation, loss of allies, kin support, and increased conspecific aggression. Dispersal strategies, such as the timing of movement and decisions on whether to transfer alone or in parallel with a peer may be associated with different costs and benefits between individuals. This research uses long-term demographic, behavioral, hormone, and ecological data to examine the triggers and consequences of 36 dispersal events from 29 male vervet monkeys (Chlorocebus pygerythrus) at Lake Nabugabo, Uganda. Dispersing adult males timed their transfer with the conception seasonality and improved their potential access to females by moving to a group with higher female-to-male sex ratio or by increasing their dominance rank. However, we argue that each transfer is unique to each individual and their own socio-ecological context.