A descriptive analysis of the climbing mechanics of a mountain goat (Oreamnos americanus)

The mountain goat (Oreamnos americanus) is one of the most extraordinary mountaineers in the animal kingdom. While observational descriptions exist to indicate factors that may influence their climbing ability, these have never been assessed biomechanically. Here, we describe whole-body motion of a mountain goat during ascent of a 45° incline based on a video recording in the Canadian Rocky Mountains, and discuss the results in a mechanical context. During the push-off phase, the hindlimb extended and the forelimb was tucked close to the torso. During the pull-up phase, the hindlimb was raised near to the torso, while the forelimb humerus seemed to "lock" in a constant position relative to the torso, allowing the elbow to be held in close proximity to the whole-body center of mass. Extension of the elbow and carpal joints resulted in a vertical translation of the center of mass up the mountain slope. Based on the observations from this naturalistic study, hypotheses for future controlled studies of mountain goat climbing mechanics are proposed.