Gait and Kinematics of Arboreal Quadrupedal Walking of Free-ranging Red Howlers (Alouatta seniculus) in French Guiana

Abstract

The understanding of the adaptive significance of primate locomotor diversity requires studies under naturalistic conditions that combine frequency of use and biomechanical analyses. Here, we report on limb kinematics and gait parameters of the arboreal quadrupedal walk of adult free-ranging red howlers ( Alouatta seniculus ). The data derive from the analysis of original video recordings shot in a primary rain forest in French Guiana. Diagonal-sequence diagonal-couplets walks largely dominated, with mean speeds of 0.67 ± 0.26 m/s. Stance duration was equal for both limbs. During the forelimb swing phase, arm abduction and protraction and elbow extension were the principal movements. Arm abduction and retraction, progressive elbow extension, and forearm pronation dominated during the stance phase. During the swing phase of the hind limb, hip flexion, thigh abduction, and knee extension dominated. Hip extension, thigh abduction, and knee extension were the main movements during the stance phase. These findings appear to support preliminary laboratory observations, provide a background for biomechanical associations, and underline the evolutionary and adaptive importance of morpho-functional complexes within the primate radiation.