Don't bump into things, especially the ground or other birds. After a bit of fine- tuning, the result was, and is, uncannily realistic. They meander around in an unmistakeably lifelike, lively, organic fashion. They bumble and swarm. The boids in the middle shimmy along contentedly, and the ones on the fringes tag along anxiously jockeying for position, and the whole squadron hangs together, and wheels and swoops and maneuvers, with amazing grace.
Real things happen.
We observe real phenomena. It is real life in an artificial medium. The great thing about studying flocking with boids, as opposed to say whooping cranes, is that the Artificial Life version can be experimented upon, in controlled and repeatable conditions. Some of these principles, while still tentative, are hotly discussed in the field. Flocking demonstrates this principle well.