The coming and go of people: group cohesion in capuchin monkeys (Sapajus flavius)
Sapajus flavius, fragmentation, cohesion, risk perception.
The intensity of intragroup food competition and the perception of risk are forces that, in interaction, generate and shape the sociality of primates, being important predictors of group size, cohesion and interindividual proximity. This study analyzed the spatial cohesion of a group of capuchin monkeys (Sapajus flavius) in an Atlantic Forest fragment in a secondary stage of regeneration on the border between the states of Paraíba and Pernambuco. We were in contact with the group for 352 hours and obtained 591 scans that contained the spatial position of each individual. We tested five hypotheses with the area of the least convex polygon weighted by the size of the group, the number of individuals in the group, the inter-individual distance and the distance to the centroid as our response variables, and the productivity of the area, proximity to edge, tree stratum, period of the day and sex/age of the individuals as predictive variables of the models. Greater fruit availability was related to smaller groups, less cohesion and greater distance from the centroid, while greater insect productivity explained greater cohesion and larger groups. The variables related to the perception of risk (ground, proximity to the edge, risky behaviors) explained the greater cohesion, larger groups, greater inter-individual proximity and in relation to the centroid. Juveniles were closer to the centroid and males were more peripheral, when juveniles were on the ground they approached females and males approached subadults. The pattern found indicates an indirect competition system characterized by greater distance when there was greater availability of fruits, spatial formation of the group (centroid-periphery) and the differential use of tree strata. While larger, more cohesive groups allowed the group to access substitute resources in areas of greater risk, during periods of reduced food supply.