An habituated group of wild patas monkeys was observed in Kenya for 550 h in 1984. Observations were made primarily during an interval that, as previous studies at the same site had demonstrated, coincided with the annual mating and conception periods. Earlier field studies of patas at other sites had reported that heterosexual patas groups had only a single resident adult male and that mating was harem-polygynous. At the Kenya site, by contrast, as many as six males were simultaneously resident and mated in the group during the conception period. Males adopted a variety of tactics to gain access to receptive females, ranging from opportunistic mating to attempts at sequestration that resembled consort behavior in other cercopithecoids such as savanna baboons and rhesus macaques. Aggressive competition for access to females took place among the males, although the number of completed copulations per male did not bear a positive relation to agonistic dominance rank. For patas monkeys, harem polygyny is only one available option within an overall mating system that is best described as a form of promiscuous polygyny, especially during periods when conception is most likely.

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Observations on a captive group of patas monkeys were supplemented with field observations to analyse the process by which a gregarious animal keeps track of the position and activity of other group members and regulates the distance between them and itself. This process can take place without the exchange of specialised signals (displays) and is described as a mechanism of group organisation alternative to a mechanism based on the exchange of displays. Displays and formalised interaction patterns can provide additional, complementary information, especially about transient features of social organisation.

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