My father is a bird watcher. One of my earliest memories is watching a giant flock of wild geese in ponds in eastern Oregon. The way the individual birds would react and interact to form what seemed like an organism was breathtaking. I bet my dad didn’t realize that this formative viewing of a flock of waterfowl would influence the way I study science.
This is a video shot by Liberty Smith and Sophie Windsor Clive from islands and rivers that shows, in exquisite beauty, how individual decisions can have cascading effects on the system. By each bird trying to optimize its distance to the bird in front and on the sides, these birds form a flock of birds. Flocking behavior, shoaling behavior in fish, and swarming behavior in insects all have similarities. Mammals, too, exhibit this behavior when they herd.
Craig Reynolds first simulated this in his “Boids” simulation (1986). The agents (the boids themselves) want to remain aligned with the other agents around them, want to retain separation from the other agents around them, and will steer their heading toward a perceived average of the headings of the other agents around them. These three simple rules produce the complexity of the flock.
Who can forget the iconic scene of the herding wildebeest in the Lion King? My understanding is that this was one of the first uses of computer graphics in an animated film, and the animation followed similar rules to Reynolds’ simulation.
While my father would likely be appalled that I would promote starlings (their negative effects on biodiversity in the Americas is well documented) this video shows flocking behavior perfectly. Enjoy the beauty of complexity.
(And thanks Joshua Garland and Brandon Hildebrand for pointing me toward this video!)