Ask a grown-up: why do birds fly in a V-shape?
Many birds fly thousands of miles during migrations. Bird flight is hard work, and their hearts beat very fast, so it can be exhausting. When birds fly together in a V-shape, they reduce the amount of effort they have to make. When a bird flaps its wings as it flies, little bits of air come off the end of its wings, trailing behind it like an invisible footprint in the sky. Any birds following behind can sit in this footprint and get a free lift, which means they are do not have to work as hard.
Imagine you were walking in the snow and following someone's footsteps – you would have an easier time following the path they left behind, becayse you would not have to work hard to crunch through the snow yourself. This is similar to what the birds are doing when they are flying in a V – though, of course, they are doing it in the sky instead.
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