Basic models of flocking behavior are controlled by three simple rules: 1) separation: avoid crowding neighbours (short range repulsion); 2) alignment: steer towards average heading of neighbors; 3) cohesion: steer towards average position of neighbors (long range attraction). With these three simple rules, the flock moves in an extremely realistic way.
@pauline oh right! And for what it's worth, my association with CARCHAR was "carceral", so I definitely missed what you intended