Agriculture, construction, search-and-rescue, environmental monitoring, and healthcare are just some of the sectors that utilize drones due to their adaptability and superior capabilities. As a result of the constant evolution of drone technology, their potential implementations are extensive and may provide solutions to new challenges in various industries. However, while the use of drones in conservation is on the rise, there has been a lack of research focusing on tropical forest ecosystems. To address this shortcoming, a lightweight drone was used to monitor wildlife in a tropical primary forest in southern Vietnam. The drone's effectiveness was evaluated during both day and night time. As a result of its compact size, the noise generated by the drone is considerably reduced, making it less intimidating to animals during photography and video recording. The results demonstrated that the drone's combination of thermal and visual sensors substantially improved its ability to distinguish between mammals with similar or dissimilar body sizes. Additionally, population sizes could be determined. Through this presentation, experience and observations regarding the use of drones in tropical forest field research will be shared. The application of drones in identifying the distribution of rarely-seen species or wild mammals in hard-to-reach areas is promising.