Wednesday, January 25, 2012

New Scientist - Goose flying upside down captured in slow-mo movie

t's a move that's sure to impress even the most skilled circus contortionists. During flight, geese can twist their necks to flip their bodies upside down, while keeping their heads upright.

Now amateur videographers Hans de Koning and Lodewijk van Eekhout have captured the first slow-mo video of the manoeuvre, winning a prize in a competition organised by the Flight Artists group at Wageningen University. Known as whiffling, the move is often performed before landing as a means of braking. Upside down wings generate more drag causing a goose to slow down quickly, just like what happens when a plane is inverted during flight. 

According to Paul Stancliffe from the British Trust for Ornithology, who has observed this manoeuvre several times in nature, what makes the move impressive is the way it allows a goose to quickly lose height. "I like the fact that this clip shows the birds turning completely upside down," he says. "It's difficult to see this happening in real time."

A picture of a flipped goose was captured by wildlife photographer Brian Macfarlane a few years ago, attracting a lot of attention since the pose has rarely been photographed. Although the twist is most common in geese and ducks, it's also used by other species of birds. "In the UK, I've observed cormorants and grey herons whiffling as well as pelicans and cranes in the Middle East," says Stancliffe.

If you enjoyed this post, watch smoke flow over an aerofoil to illustrate how wings create lift or check out a somersaulting fly captured in slow-mo, one of the other competition winners.

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