From schools of fish, to swarms of insects, to flocks of birds, many animals live and move in groups. They have no leader, no central coordinator, and yet manage to perform awe-inspiring coordinated displays of collective motion. These swarming behaviors are archetypal examples of how local coordination between nearby animals translates into an emerging global behavior. But how localized should this local coordination be? Is more interaction always better? Not all animal taxon swarms, and observations of flocks of starlings show that they limit their interaction to their six-to-seven nearest neighbors.