University of Colorado at Boulder – A new study indicates that the Red Kangaroo uses its tail as a pseudo-leg when grazing.
Researchers at several different colleges have noticed that the kangaroos push themselves around the ground using their tail as they graze. This not only helps them stay balanced as they walk, but also as they bend over to eat.
“We found that when a kangaroo is walking, it uses its tail just like a leg,” said Associate Professor Maxwell Donelan of Simon Fraser University, corresponding author for the study. “They use it to support, propel and power their motion. In fact, they perform as much mechanical work with their tails as we do with one of our legs.”
“We went into this thinking the tail was primarily used like a strut, a balancing pole, or a one-legged milking stool,” said Associate Professor Rodger Kram of CU-Boulder’s Department of Integrative Physiology, a study co-author. “What we didn’t expect to find was how much power the tails of the kangaroos were producing. It was pretty darn surprising.”
The Red Kangaroo lives in Australia, where it is the largest native mammal on the continent. They mostly feed on grass, which can make up over half of their diets. The animal looks incredibly awkward as it eats its favorite food, as the kangaroos use their front limbs to hold themselves up and their tails to keep balanced.
“They appear to be awkward and ungainly walkers when one watches them moseying around in their mobs looking for something to eat,” Rodger Kram, a CU-B physiology associate professor, said in the release. “But it turns out it is not really that awkward, just weird.
For the study the team videotaped five red kangaroos in Dawson’s Sydney lab that had been trained to walk forward on a force-measuring platform with Plexiglas sides. The platform’s sensors measured vertical, backward and forward forces from the legs and tails of the animals. The kangaroos had been taught that walking forward on the platform resulted in being rewarded with sweet treats, said Kram.
Over his career Kram and his students have studied the locomotion of a number of creatures, from elephants, tortoises and llamas to ostriches and beetles.
Although much of the data for the new study was collected years ago, other research efforts by the team members slowly pushed some of the key kangaroo locomotion data to the back burner. “But this was a study we just could not let go of,” said Kram. “It was just too much fun. It’s a real wonder of nature, how these kangaroos move about and what they are able to do.”
The video, published by researchers at the University of Colorado at Boulder, of the Red Kangaroo walking is available here.
The CU-B, Simon Fraser University, and University of New South Wales researchers published their study in the journal Royal Society Biology Letters.