Ravens against an orange sunset

Photo: Radek Mica/AFP/Getty Images

A massive flock of ravens from northern Poland and Russia arrive in the southern Czech town of Zidlochovice on Nov. 27 as the sun sets behind tall grasses and trees.

The group of birds (which are actually called an "unkindness" in their collective form) are migrating south for the winter to avoid the cold weather. They're expected to return north in March.

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Ravens fly against a sunset

Photo: Radek Mica/AFP/Getty Images

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Ravens against a blue and pink sunset

Photo: Radek Mica/AFP/Getty Images

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Catie Leary is a photo editor at Mother Nature Network. Follow her on Twitter and Google+.