Watch the shortened version above to see how smoothly the birds move and hear the calming sound of their wings flapping: A murmuration is when a large group of starlings flies through the sky to look like they are dancing. It seems like a wavering cloud that quickly changes direction, density, and shape as it moves through the sky. Because it was a mild winter in the Netherlands between 2014 and 2015, many starlings didn’t leave the country to go south. Jan van IJken made a short film called The Art of Flying about one of these air shows. You can watch the whole thing on his website.