How Mountain Goats Ascend Nearly Vertical Cliffs

June 20, 2016 | Erica Tennenhouse

A sheep on a steep cliff
Photo credit: JulieK/ (CC BY-NC-ND 3.0)

The climbing mechanics of extraordinary mountaineers.

Mountain goats can powerfully scale up the most precipitous slopes with the grace of hooved ballerinas. They have a knack for verticality, and now researchers have a better idea why.

The bodies of mountain goats are machines built to climb. Their hooves have a hard outer case that allows them to dig into almost-invisible ledges. Soft pads on the bottoms of their hooves mold to contours in the mountain’s surface like climbing shoes. And while their bodies appear thick and muscular from the side, mountain goats are actually slender when viewed head-on; this shape is conducive to maintaining balance on narrow protrusions.

Though these physical adaptations are apparent, little is known about the mechanics involved in their movement. Sightings of mountain goats in climbing motion are relatively rare due to the inaccessible terrain in their remote habitats.

Biomechanics researchers Ryan Lewinson and Darren Stefanyshyn from the University of Calgary obtained a YouTube video of a male mountain goat climbing in the Canadian Rocky Mountains and analyzed his movements frame by frame to find out how these sure-footed climbers manage to scale nearly vertical surfaces.     

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When mountain goats pull themselves up the side of a cliff, their muscular shoulders give them a considerable boost. Thus, the researchers expected that the main point of rotation when the goat’s front hooves were on the ground would be the shoulder joint.

However, on watching the video, they observed that the primary point of rotation during the portion of the climb when the goat’s front hooves were in contact with the slope was actually well in front of his shoulder. This suggested that the mountain goat’s thick neck might provide an additional muscular advantage during the climb.

“The first aspect that stood out as key to mountain goat climbing was that the muscles of the neck might play a larger role in climbing than we originally thought,” Lewinson told The Science Explorer. “Together, the shoulder and neck muscles of the goat seem incredibly powerful.”

They also noticed that the mountain goat appeared to strategically keep his elbow close to his body’s center of mass while climbing. This result of this approach was that when he extended his elbow, he propelled his body straight upwards rather than rotating his torso.

The full description of the climbing mechanics of the mountain goat will soon be published in the journal Zoology.

“I’m sure anyone who has seen these animals in action has been impressed by what they can do, and probably asked themselves ‘how on earth do they do that?’” Lewinson said.

“As the wildlife biology expert, Douglas Chadwick writes in his book, A Beast the Color of Winter, the mountain goat ‘…is possibly the best and most complete mountaineer that ever existed on any continent,’ and I would agree.”

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