This comprehensive research has provided much insight into their behavioral relationships. This summer our primary goal was to monitor different male strategies, as part of a longer project with the goal of determining how variation in male strategies affects reproductive success. It seems to be very costly to retain the status of resident male because the male must keep other males, reproductive competitors, out of the group. Since 1994 behavioral data have been collected on the sexual activities of the monkeys. These observations have been made primarily by following estrous females and adult males.
Copulations are relatively rare events and can often happen in inconspicuous places.
Also, the group can be very spread out in a visually dense environment and the sneaky behaviors of males and females make team work by observers a necessity. It takes many researchers to follow and to monitor the individuals in the group. Male-male interactions are also monitored to see if there is a connection between their dominance rank and reproductive success. Dominant males might be expected to have priority of access to resources like fertile females, and therefore higher reproductive success. But this need not be true because mating behavior is determined by a complex set of factors.