Boids where originally invented/described by Craig Reynolds, and presented at the 1987 SIGGRAPH. His original paper can be read here.
Boids particles are built into the Blender particle system, but if you are using Cinema 4D check out this awesome and free plugin, Flock Modifier.
Years ago when I was new to 3D and was using Blender I made some flocking bird (boids) particles for a DVD menu. I found the original project, its pretty basic. Here it is. Enjoy.