Goodrich, Ellie; Seaboch, Melissa (University of Utah)
Faculty Advisor: Seaboch, Melissa (University of Utah, Anthropology)
Alouatta palliata (the mantled howler monkey) form large, cohesive multimale multifemale groups. Within these groups there are prominent male dominance hierarchies and both males and females disperse from natal groups. Although A. palliata groups are cohesive, interactions among individuals are rare. Spatial relationships in primate groups aren't random and are often telling of the underlying social structure within a group. This project compares three adult dyads in the A. palliata groups of La Selva Biological station, Costa Rica, to examine group cohesion and if there is variation in spatial patterns between the dyads. The dyads include male-male, female-female, and male-female. Data were collected from May 11-May 22 , 2017 and May 11- June 19, 2018. Instantaneous scan samples were taken at two-minute intervals, and for each scan the sex of each individual, the nearest neighbor's sex, and proximity to closest neighbor were recorded. Proximities were visually estimated to the nearest half meter and sex was determined by body size and the presence or absence of scrotum. The data showed that males maintained closer distances with females than with other males, and females maintained closer distances with females than males. The average male-male distance was 4.2 meters, female-female 1.51 meters, and male-female 2.68 meters. The results suggest that sex plays a role in the spatial organization of a group. In A. palliata adult males have been found to rarely interact with other males and will often employ avoidance strategies, explaining the distances observed between males in this study. Female-female dyads tend to maintain closer and more affiliative proximities due to the presence of infants and the lack of competition for mating and food resources. There are also more females present in A. palliata troop than males, increasing the likelihood that males would be in proximity to females rather than other males.