the forces acting on the birds are as follows:

• WANDER: the birds move forwards with a slightly randomized direction

• COHESION: the birds are drawn towards their "neighbors," that is, other birds within a certain distance

• SEPARATION: the birds try to avoid hitting each other

• AVOIDANCE: the white birds stay away from the red birds

to illustrate how the idea of neighbors works, one bird starts out blue. Every bird they consider their neigbor also turns blue.