On winter evenings in some southern European towns, tens of thousands of starlings congregate over their roosts. Above the ruins of Rome’s ancient Baths of Diocletian, huge black clouds of starlings assemble and continually morph into new shapes, possibly to signal their position to buddies who are still navigating their way home.
Scientists have proposed several explanations for how bird flocks, fish schools, and other large groups of animals coordinate their acrobatics, especially when they have to quickly change course to avoid predators, says Andrea Cavagna, a physicist at Italy’s National Research Council (CNR) in Rome. The assumption has been that individuals match their trajectories to those of all animals within a given distance.