Why do birds fly in a V?
We have all heard the honking of geese passing overhead, looked up and seen a group of birds flying in a V shape. Military airplanes do it too ― they adopt a V formation when flying in groups.
Birds form the shape because it improves the efficiency of flying. If you have a long way to go, any saving will be valuable, and for large migrating birds such as geese and ducks, the energy saved can be significant.
So how does it work? It’s all to do with aerodynamics. As a bird flaps its wings, it creates an “upwash” of air on the downstroke. If the bird is flying right behind another bird, it can catch the upwash and use it to help push itself higher. It means the bird doesn’t have to put quite so much effort into its own downstroke.
Of course, this only works for birds flying behind. The leading bird doesn’t have any upwash to catch and has to put full effort into flying, which is tiring. To spread the benefit, all the birds take turns at the front. By sharing the duties like this, the overall energy saved can be around 65 percent, and it allows the birds to fly up to 70 percent farther than if they flew on their own.
And it only works if the bird times its wing beats to catch the upwash. So birds adjust their position and the timing of their flapping to make sure they are in the best position.
・words & phrases
is all to do with 〜と関係している
aerodynamics 空気力学
upwash 上方への気流
downstroke 下への動き
on their own 単独で
times its wing beats 良いタイミングで羽ばたく
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