Camera traps have commonly been used to document the presence of medium to large-sized mammals in tropical forest ecosystems, as they are non-invasive and sample continuously with little human interference. These camera traps have traditionally been placed at ground level; however, more recently arboreal camera traps have been deployed to document arboreal and semi-arboreal species, such as primates, in these same systems. Despite this, the amount of additional information learned from arboreal cameras in terms of distribution of species has not yet been explicitly studied. Therefore, using camera traps deployed at 3 heights, ground-level, mid-canopy, and high-canopy we sought to quantify the amount of information collected by each camera across a landscape for primate species. We used data collected in a 2019 study from Bwindi Impenetrable Forest National Park, Uganda. Our results showed that for the 9 primate species found in the park, 5 were detected at ground-level, 8 were detected in mid-canopy, and 8 were detected in high canopy. Only one species, the mountain gorilla, was only detected at ground-level, while 4 species, were only detected in mid- and high-canopy. All species detected by arboreal cameras were detected by both mid- and high- canopy cameras. In terms of distribution, by including arboreal cameras, primate species were detected on average at 25% more sites than detected by ground cameras alone, with a range from 0% to 75% more sites per species. When taking into account detection probability, the increase in occupancy when arboreal cameras were used in addition to ground cameras was on average 0.280, with a range from -0.049 to 0.816. Our study shows the importance of including arboreal camera traps in addition to ground camera traps when surveying primates in a tropical forest. Without the addition of these cameras, occupancy and distribution is underestimated in most species, which can lead to erroneous conclusions about the health of the populations.
arboreal camera traps, primates, species distribution, canopy