Pull up, Rocky, pull up! Flying squirrels look reckless as they fling themselves through the air, but there's finesse to their swooping. Rather than gliding passively like paper airplanes, the rodents actively manipulate the furry membrane that stretches between their wrists and ankles to control the speed and direction of their flight, new research published online today in the Journal of the Royal Society Interface reveals. The scientists set up video cameras in a Maine forest and analyzed recordings of animals lured to a feeder, and then compared the squirrels' glide-path trajectories with aerodynamic simulations. Rather than cruising through the air at a constant speed, the team found that the squirrels continuously modulate their speed and direction to attain distance and lift. This contradicts aerodynamic models of the evolution of flight, which assume that a transition from gliding to flapping would have been too mechanically awkward and unstable. According to the authors, the fact that flying squirrels have the sensitivity and physical ability to adjust their "wings" to fly more precisely suggests that gliders may indeed have been evolutionary precursors to creatures that flap, such as bats or birds.
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