Positional behaviour and tail use by the bare-tailed woolly opossum Caluromys philander (Didelphimorphia, Didelphidae)

We present the first quantitative description of postural behaviour of a free ranging metatherian, the bare-tailed woolly opossum, Caluromys philander. Postural behaviour was observed using 10 camera traps set in front of artificial nests, located in the understory of an Atlantic forest site in Rio de Janeiro, Brazil. Seven locomotory and positional modes were identified, with a predominance of diagonal couplets. Individuals used three types of grasp as observed in captivity, but the frequency of digital grasping was higher in the wild. The tail was used as an additional grasping limb, preventing falls and freeing hands to other activities, but the tail was also used to carry leaves for nest building. The use of camera traps may represent a breakthrough in the study of positional behaviours in the wild.