In winter as evening descends in Rome, Montpellier, France, and perhaps near you, a beautiful and awesome pageant is presented by thousands of starlings. They fly in clouds of dramatic shapes that change for many minutes. They rise, fall, twist, rise, fall… and finally settle on trees for the night. It’s unforgettable.
So, who’s leading the performance? How does each bird catch signals from the rest of the flock and then respond to generate the elaborate pattern? Ornithologists suspected many signals being exchanged by every bird. Can the bird brain, or even the human brain, track that much information?
In Rome, a team of computer programmers and physicists proposed otherwise. Then a team led by the husband-and-wife team of Andrea Cavagna and Irene Giardina climbed to rooftops in Rome with paired cameras to image where every bird was in these “murmurations”. Surprising, or not, the images showed that individual birds responded to the positions of only about 7 neighbors. Each bird moves almost randomly but faster than the cloud itself. The flock’s behavior is self-organizing, other than at the edges of the great cloud.
Source: Nat Geo Apr. 25, pp. 108 ff. and Proceedings of the Royal Society B, 7 April 2013
Image: starling murmuration 1.jpg National Geographic - https://www.nationalgeographic.com/animals/article/graphic-starling-murmurations-dazzling-ubiquitous-puzzling
