Thursday, January 16, 2014

V is for vortex

The northern bald ibis (Geronticus eremita) was once such a widespread sight in the skies of north Africa that the bird was immortalized as an ancient Egyptian hieroglyph. The picture symbol denoted the word akh, which means ‘to be resplendent, to shine’. Ibis populations are less resplendent today, with just a few hundred of the wild birds remaining, mainly in Morocco. They can still shine, however; a study of 14 northern bald ibises reported this week on page 399 offers the first experimental evidence that helps to resolve one of the great questions of the natural world: why do migrating birds often fly in an elegant V formation?
The obvious answer is that it saves energy. Just as the mass ranks of a peloton in a cycle race make life easier for riders, and as tight formations can save aircraft fuel, the signature shape of a flock of ibises or geese is assumed to make flight less of a flap — at least for the bulk of the birds that follow the leader. (That is another, less obvious, theory for the V shape: that the bird at the front is the best navigator.)

Source: Here

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