Breathtaking "murmurations" - dark, shifting shapes that look like vast dancing clouds - fill the skies of southern Israel and surrounding areas in winter.Starlings from Russia and east Europe winter in Israel, swooping, pivoting and soaring, putting on a display to shame any aerobatics team anywhere.They embark on their spectacular aerobatics in the evening. By grouping together, the starlings not only find safety in numbers but their changing movements and shifting collective shape confuses their would-be attackers, experts say. They can even create a sudden breeze with their synchronized movements, causing a hawk or falcon to fall flat on its back, not unlike an aircraft hitting windshear.Until 20 years ago, starlings came to Israel in their millions, usually descending on the northern part of the Negev desert, which remains warm in winter. But for unknown reasons their numbers have dropped. In the past few years they have come in flocks of no more than a few hundred thousand.