Social Dynamics and Activity Patterns of the Endangered Alouatta caraya in a Fragmented Cerrado Forest in Southeastern Brazil

We studied a group of howler monkeys (Alouatta caraya) in Dumont, São Paulo, Brazil, inhabiting a highly fragmented 9.88-ha riparian forest within the Cerrado biome, affected by agriculture, cattle ranching, and clay extraction. This critical scenario poses a local extinction risk, as highlighted in São Paulo’s Red Book. Additionally, this species has been suffering from yellow fever epizootics and, in the near future, may also face extinction due to inbreeding. While their folivorous diet aids adaptation to degraded areas, the role of social relationships in isolated groups remains understudied. Using the scan sampling method, we recorded 30 behavioral categories and classified individuals into five sex-age groups: adult male (AM), adult female (AF), sub-adult male (SAM), juvenile (JUV), and infant (INF). Behavioral patterns were analyzed using principal component analysis (PCA) to identify social functions within the group. Despite habitat fragmentation, the monkeys' behavior aligned with findings from studies in conserved areas. AFs showed higher frequencies of intra-group maintenance behaviors, suggesting a matrifocal structure, while AMs exhibited dominant and territorial behaviors. Only JUVs and INFs engaged in play, and SAMs occupied the group’s periphery. AM territoriality may also contribute to group cohesion, warranting further study. A division of roles between AFs and AMs was evident. Although howler monkeys demonstrate behavioral plasticity, further research is needed to understand their persistence in the increasingly fragmented Cerrado biome of São Paulo, Brazil.