Parkour is a form of freerunning, is a popular sport where people jump over and under obstacles at speed and often involves leaping long distances.

A team of US-based researchers at University of California, Berkeley studied the biomechanics of bounding squirrels in eucalyptus trees and observed how and when they flung themselves from one branch to another. 

Researchers hope that the findings can be used to improve artificial intelligence systems and robotics to create machines that are able to nimbly navigate terrain.

“As a model organism to understand the biological limits of balance and agility, I would argue that squirrels are second to none,” said Dr Nathaniel Hunt, the co-author of the study.

“If we try to understand how squirrels do this, then we may discover general principles of high performance locomotion in the canopy and other complex terrains that apply to the movements of other animals and robots.”

Mind the gap

Wild squirrels were enticed with peanuts and observed with high-speed cameras to capture every contortion of their body as they navigated the trees.

The team changed the strength of the branches, the length of the gap between take-off and landing, and also the position of the touch-down spot.

“When they leap across a gap, they decide where to take off based on a trade-off between branch flexibility and the size of the gap they must leap,” said Dr Hunt.

The study, published in the journal Science, also found that even when faced with a new situation, the squirrels were able to use their extensive knowledge, as well as trial and error, to figure out the best route in less than five attempts.

Freerunning methods

To reach the highest branches, the researchers found the squirrels used parkour-like methods.

“Squirrels consistently used the parkour manoeuvre for the medium and long leaps (ranging 3 to 5 bodylengths) but never for short leaps (1.5 bodylengths),” the researchers wrote.

The study found that the squirrels rarely made a perfect leap, but their flexibility and mid-air adjustments meant none of the rodents in the study fell.

Dr Hunt said: “They are not always going to have their best performance. They just have to be good enough. They have redundancy. So, if they miss, they don’t hit their centre of mass right on the landing perch. They are amazing at being able to grab onto it.

“They will swing underneath, they’ll swing over the top. They just don’t fall.”