Abstract
Arboreal mammals, particularly nocturnal species, are one of the least studied mammalian groups but make up a significant percentage of mammalian species richness in the tropics. The challenging conditions involved in observing this group has led to a bias towards studying ground dwelling mammals. Yet nocturnal arboreal mammals, highly adapted to their environment, perform important ecological services such as seed dispersal and pollination. Reducing this bias is needed to develop holistic conservation plans for threatened tropical forests. We used thermal and night vision binoculars from a portable elevated platform in a tropical forest in Panama to conduct nocturnal mammalian surveys. We simultaneously conducted two camera trap surveys, one ground-based, one arboreal, in order to compare the methods with respect to species detection and cost/effort. All methods combined recorded 32 ground dwelling and arboreal species and elevated nocturnal observations recorded the most of any single method with 69% of recorded species compared to 66% for ground-based and 47% for arboreal camera traps. Importantly, elevated nocturnal observations detected more nocturnal arboreal species over 12 survey nights (13 species) compared with 806 arboreal camera trap nights (8 species). Cost/effort analysis showed the use of thermal optics from elevated platforms is not more resource heavy because less time is needed to inventory species. Whilst arboreal camera traps remain an important tool for studying species distributions over large spatiotemporal scales, our study demonstrates the use of thermal optics from an elevated platform is a complementary survey method for arboreal mammals in a tropical application, particularly for rapid inventory and behavioural studies.