Tails in Action: Comparative Use of the Prehensile Tail and Substrate in Alouatta macconnelli, Sapajus apella, and Potos flavus.

Arboreal habitats are three-dimensionally complex and are composed of substrates that differ in size, compliance, and continuity. In response, arboreal vertebrates have evolved morphological and behavioral traits allowing them to successfully move through these environments. Prehensile tails constitute one of such adaptations, yet remain poorly studied. Variation in prehensile tail use between species might result in anatomical variations, as has been shown in primates but remains undocumented in most species. The present study, therefore, sought to describe prehensile tail use and substrate type utilization between two primates, the Guianan red howler (Alouatta macconnelli) and Brown capuchin (Sapajus apella) and one carnivoran, the Kinkajou (Potos flavus). To do so, we used 1431 photographs obtained from camera traps placed in the canopy in French Guyana. The results showed that P. flavus exhibits a greater diversity of overall positional and prehensile tail-associated behaviors compared to S. apella and A. macconnelli. Moreover, P. flavus used its tail for both stability and mass-bearing purposes during locomotor and postural behaviors, while A. macconnelli and S. apella used their tails mainly for mass bearing and stability, respectively, and this was only during postural behaviors. P. flavus mostly used large substrates but A. macconnelli used more small substrates. S. apella showed a preference for both medium and large substrates. Multivariate analyses showed that the three species were well discriminated regarding positional behaviors, with P. flavus exhibiting several postural and especially locomotor behaviors not shared by the two primate species, as well as a combination of behaviors shared with either of the two aforementioned species. A. macconnelli was mainly characterized by suspensory posture and vertical displacements, whereas S. apella mainly used above-branch postures using its tail to anchor itself.