Birds are good at not crashing into stuff. So good that it鈥檚 easy to take their ability to avoid trees, telephone wires, and other birds for granted. But Harvard biologist David Williams wanted to know how, exactly, birds avoid close calls.
So Williams set up an obstacle course in his lab: a series of white poles spaced closely together. He watched as pigeons tested their mettle, catching their movements with high-speed cameras as they flew around the room, and through the gaps between the poles.
Reviewing the footage, he found that agile fliers adopt one of two postures to avoid a collision, wing pausing and wing folding:
In the 鈥減aused鈥 configuration, the pigeons stopped flapping right before the obstacle, exactly at the moment when their wings were up above their bodies, at the very top of the stroke. With their bodies thus tall and skinny, rather than wide, they could pass through. In the 鈥渇olded鈥 configuration, the birds hugged their wings close to their body as they darted through the opening, again minimizing their width.
While the 鈥減aused鈥 posture is speedier, as it鈥檚 less disruptive to flight, the 鈥渇olded鈥 posture is safer: with its wings wrapped around it鈥檚 body, the bird is better protected in the event of a crash.
Surprisingly, these two tricks seemed to be the only ones the pigeons had up their, erm, wings, : 鈥淲e thought it would be catch-as-catch-can, and it鈥檚 not.鈥 The researchers didn鈥檛 document the birds rotating, or trying to pass with one wing up and one wing down.
That doesn鈥檛 mean the birds don鈥檛 employ other obstacle-avoidance positions. Next up, Williams will test the pigeons on horizontal obstacles that mimic tree limbs and record their fancy flight work.