Determinants of Daily Path Length in Alouatta guariba in a Continuous Forest

Abstract Spatial use patterns in primates result from complex interactions among individual characteristics, physical, and ecological factors, such as temperature, food availability and distribution, and conspecific and heterospecific encounters. Understanding how these factors integrate is essential for interpreting variation in species' movement patterns. In this study, we evaluated how minimum temperature, day length, diet, rest and activity time, and social interactions influence the daily path length (DPL) of a group of brown howler monkeys ( Alouatta guariba ) sharing their habitat with muriquis ( Brachyteles arachnoides ), capuchin monkeys ( Sapajus cucullatus ), and black lion tamarins ( Leontopithecus chrysopygus ) in a continuous Atlantic Forest fragment, Brazil. We hypothesized that DPL is modulated by the integration of physiological constraints, ecological pressures, and dynamic social interactions. We followed the focal group for 22 full days between August 2023 and January 2024, recording GPS locations and behaviors at 5-min intervals, along with encounters with conspecific and heterospecific primates. A structural equation model based on Partial Least Squares Path Modeling explained 70% of the variation in DPL. Environmental variables (minimum temperature and day length) were positively associated with rest time, while both rest time and leaf consumption were negatively associated with path length. Encounters with heterospecifics were positively associated with displacement, while fruit consumption, conspecific encounters, and activity time showed no significant association. Collectively, these findings highlight the importance of simultaneously integrating ecological and social variables to understand the spatial organization of primates in continuous habitats.