Human activity can lead to changes in animal behavior and distribution patterns if the level of activity is high enough to cause disturbance. Both humans and other animals commonly use human-made trails in lowland tropical forest and, therefore, it is possible that use of trails by humans might affect the likelihood that animals would use those same trails. We investigated this possibility at a site in lowland forest of eastern Ecuador using camera traps to document numbers of people and numbers of other animals at a series of camera locations during January–March, 2014–2016. Human activity was higher on trails used by all visitors to the research station than on two research plots where human activity is restricted. Ungulates were the only group to show a strong negative relationship with human activity but only on trails open to all visitors; there was no apparent negative impact of human activity on research plots. Results suggest that the level of human activity along trails is not now causing negative impacts to most mammals but also that levels of activity should be monitored to ensure that any increase in human presence does not lead to negative responses by mammals.