Arboreal Camera Trap-based Insights into the Activity, Resource Use, and Demography of Black Lion Tamarins (Leontopithecus chrysopygus) and Sympatric Mammals in Atlantic Forest Fragments

Abstract Wildlife monitoring is essential for guiding biodiversity conservation strategies, particularly in fragmented ecosystems under intense anthropogenic pressure. While noninvasive methods, such as camera traps, are widely used for terrestrial species, their application in other forest strata is underexplored despite its potential for studying elusive and nocturnal arboreal mammals. We aim to evaluate whether arboreal camera trapping is a relevant tool for monitoring the endangered black lion tamarin ( Leontopithecus chrysopygus ) and other sympatric arboreal and scansorial mammals in two Atlantic Forest remnants in Pontal do Paranapanema, São Paulo, Brazil. With 27 cameras in the lower and mid-canopy (0.5–8.0 m) and 9,872 camera-days, we recorded 1,316 independent video events representing seven species of mammal. Arboreal camera traps provided robust estimates of diel activity patterns, resource partitioning, and demographic dynamics, including the development of one tamarin infant and one juvenile over time. They also revealed interspecific sharing of sleeping sites and nest boxes, emphasizing the role of these structures in supporting both diurnal and nocturnal species. By documenting community-wide temporal niche partitioning, our study demonstrates how arboreal and scansorial mammals segregate activity in time when sharing the same arboreal structures. Overall, our results show that arboreal camera traps are relevant, noninvasive tool that simultaneously capture species-specific behavior, community-level interactions, and demographic information, highlighting their value for primatology, biodiversity monitoring, and integrative conservation planning in human-modified tropical forests.