Species in the genus Alouatta Lacépède, 1799 are social, and their groups display considerable variation in their age and sex composition. Little is known about the social organization of groups of Alouatta guariba clamitans Cabrera, 1940. This study was carried out between February 2002 and June 2004 in the Chácara Payquerê, located in the municipality of Balsa Nova in the state of Paraná (Southern Brazil). The vegetation in this area is the Araucaria Pine Forest, and this reserve is located within the Area for Environmental Protection of the Devonian Scarp. During observations, groups were identified and their sex/age composition and dynamics were recorded. Six groups were observed over the course of three years. Average composition values were 6.33 individuals/group; 1.47 adult male (AM)/group; 0.46 subadult male/group; 2.2 adult females (AF)/group; 1.13 juvenile II/group; 0.8 juvenile I/group, and 0.27 infant/group. In order to describe the sex/age composition of this species, the data obtained in the present study were combined with information on 66 additional groups of A. g. clamitans available in the literature, totaling 72 groups. Ensemble values obtained for this species are 6.25 individuals/group; 1.39 AM/group; 2.26 AF/group and 2.62 immature individuals/group. With respect to the dynamics of the groups, the following data were recorded: 11 births, 25 age class changes, 4 solitary individuals, 1 death/disappearance, and the fission of one group into two. Therefore, the current study described the the sex/age composition of A. g. clamitans groups, as well as some aspects of their dynamics.
Brown-howler monkey; ecology of populations
