Reading1: Flocks, Herds, and Schools: A Distributed Behavioral Model, C. Reynolds, SIGGRAPH, 1987 (html)
Reading2: Stable Flocking of Mobile Agents, Part II, Tanner, Jadbabaie, Pappas, IEEE Conf. on Decision and Control, 2003 (Paper pdf) [Note: Aim to try and get the gist of the proof structure, rather than details]
Review Assignment: Submit a review comparing the approaches to modeling flocking in both papers.
Optional Extra: Nice movie of starlings being chased by a hawk. movie
Also if you are interested in this area, see "Effective leadership and decision making in animal groups on the move", Couzin et al, Nature 2005 (pdf) and other work by Couzin's lab on fish schooling and group predator avoidance.