I was watching a bunch of birds the other day and I took note of their flocking behavior. I found it so intriguing that I decided to do some research. After reading all that I could find on the subject, I’m left with a sense of inadequacy with the theories. Everything I read indicated that the principles of flocking have to do with a sort of polarization - the birds are all aimed in the same general direction and take course corrections from their neighbors. Also, there’s a sort of collective homing mechanism that controls the fundamental direction of the flock. All sources agreed that there is no leader.
All that makes sense, when the flock is migrating, but it seems to fall apart when viewed with the behavior I was witnessing. Let me try to describe it. The birds seemed to be feeding. They started out in a tree. There were a lot of them; a hundred or more. As if a single unit, all of the birds dropped out of the tree and began to feed. Their flight from the tree was anything but polarized. As they left the tree they were fairly orderly, but in mid flight, they seemed chaotic, more like a swarm. However, when they touched down, they seemed to be reoriented in basically the same direction again. They fed for about 30 seconds, milling about at random on the ground, then as a single unit they ‘jumped’ back into the air. At first I thought that they were headed back to the tree, perhaps startled by something. There were two problems with this assumption: (1) There was no apparent source of ‘startlement’ and (2) they didn’t go to the tree. They just flocked over to a new feeding location. The route they took, by the way, seemed entirely random. As a group they darted this way and that, only to land in the new location as a group again. I watched a few minutes longer and again the flocked jumped to a new location. Finally, the entire flock jumped back into the tree. Through this entire episode, their timing seemed instantaneous. All of the birds seemed to decide that a particular feeding location was exhausted simultaneously. Their departure direction seemed predetermined. Frankly, it’s hard to see how they could possibly react that fast and that precisely even if they were following a leader… it’s even harder for me to fathom that this behavior is possible without a leader. Certainly a collective intelligence couldn’t process direction changes that fast. Also, in this kind of scenario, it seems unlikely that there’s any collective homing mechanism setting their course direction. However, I’ve been watching a lot over the last several weeks and it certainly doesn’t look like there is a specific leader either…
Note: My question is not about how flocks form or why - It’s about how flocks, as units, align to a specific goal. I know about boid theory. This explains how the flock is formed and why it is cohesive, but doesn’t explain how the flock knows where to go and when. In most of the interesting boids demonstrations I’ve seen, there’s a cheat added. One or more of the boids is given special directives that has the tendency to drive an element of randomness in the swarm direction (in other words, there’s either a leader or all of the boids have a common ‘mind’, giving them a common goal). True-to-life boids demonstrations tend to be uninteresting because the flock just moves in a straight line from one ‘side’ of the simulation environment to the other ‘side’.
Any flocking experts out there?