Moving up the dominance hierarchy in young sooty mangabeys

Abstract

In contrast to the matrilineal dominance system reported for several primate species, sooty mangabeys, Cercocebus torquatus atys, exhibit a dominance system that is independent of matriline except in the first years of life. Beginning as early as 2-3 years of age, juveniles may begin to outrank both their mothers and other initially higher-ranking individuals. The present study followed 12 juvenile sooty mangabeys ranging in age from 2 to 5 years over a 6-month period to assess the means by which higher dominance rank is attained. Four behavioural patterns were identified: (1) directly challenge a higher-ranking animal (57·1%); (2) join with an aggressor against a higher-ranking opponent (27·6%); (3) challenge a higher-ranking individual while seated next to or in the general area of (and/or grooming) an even higher-ranking animal and then enlist their support against the former (13·4%); and (4) challenge a higher-ranking animal when an adult male is in the area and enlist support of the male (1·8%). The use of the above strategies was not affected by age group or sex. The main points of interest are that juvenile sooty mangabeys do move up the dominance hierarchy using a variety of behavioural patterns and that this is accomplished without aid from matrilineal kin.