How Do Starling Flocks Create Those Mesmerising Murmurations?
by Andrea Alfano, Cornell Univ.
Would you pull over your car just to watch some starlings? A gathering of only a few of these speckled, iridescent-black birds isn’t a very alluring sight—particularly in North America, where these birds are invaders. The European Starling was originally introduced here by a group of well-meaning Shakespeare enthusiasts in 1880, but many Americans now consider them to be pests that serve little purpose other than to dirty car windshields and destroy crops.
But Grainger Hunt, a senior scientist at the Peregrine Fund, tells a different story in Living Bird magazine. He marvels at the way thousands of the birds gather in flocks called murmurations. They are “a dazzling cloud, swirling, pulsating, drawing together to the thinnest of waists, then wildly twisting in pulses of enlargement and diminution,” he writes. It’s certainly worth stopping your car for, or stopping to watch a video like this one, a YouTube hit recorded over the River Shannon, Ireland.
Almost always, Hunt writes, these aerial spectacles are caused by a falcon near the edge of the flock. It turns out that the beauty of a murmuration’s movements often arises purely out of defense, as the starlings strive to put distance between themselves and the predator.
So how do these masses of birds move so synchronously, swiftly, and gracefully? This isn’t an idle question—it has attracted the attention of physicists interested in how group behavior can spontaneously arise from many individuals at once. In 2010, Giorgio Parisi of the University of Rome and colleagues used advanced computational modeling and video analysis to study this question. They found that starling flocks model a complex physical phenomenon, seldom observed in physical and biological systems, known as scale-free correlation…