Jumping squirrels rotate to brake as they mind the gap

Jumping squirrels rotate to brake as they mind the gap Since London Underground began cautioning passengers to 'Mind the gap' in 1968, similar warnings have proliferated from Hong Kong and Jakarta to Seattle and So Paolo.But the voids that human passengers clear when disembarking from trains are nothing compared to the distances that squirrels span when they leap from branch to branch.Yet squirrels lack a vital attribute that might seem essential for a life bounding through trees: a grasping hand.Even though squirrels can clutch a nut, they cannot clasp a branch as they hurtle by.Instead, the rodents land palm down on a branch as they reach out, somehow swinging their body to rest with perfect dignity.But if the span is too long or short, squirrels might require more manoeuvrability when they botch a landing.Intrigued by the forces that allow agile squirrels to land safely despite their lack of grasp, Sebastian Lee [University of California (UC), Berkeley, USA] and colleagues rigged a horizontal wooden pole with sensors to record the forces exerted by fox squirrels (Sciurus niger) as they landed leaps.