and why animals evolve grouping behavior. We thank Art Covert and the Freshman Research Initiative at The University of Texas at Austin for their support through the development of this project. This research has been supported by the National Science Foundation BEACON Center under Cooperative Agreement DBI-0939454, and Michigan State University through computational resources provided by the Institute for Cyber-Enabled Research. Acknowledgements References 20 [6] R.E. Kenward. Hawks and doves: Factors affecting success and selection in Goshawk attacks on Woodpigeons. Journal of Animal Ecology , 47:449–460, 1978. [5] M. Treisman. Predation and the evolution of gregariousness. I. Models for concealment and evasion. Animal Behaviour , 23:779–800, 1975. [4] H.R. Pulliam. On the advantages of flocking. Journal of Theoretical Biology , 38:419–422, 1973. [3] Brian C.R. Bertram. Vigilance and group size in ostriches. Animal Behaviour , 28:278– 286, 1980. [2] Ashley J. W. Ward, James E. Herbert-Read, David J. T. Sumpter, and Jens Krause. Fast and accurate decisions through collective vigilance in fish shoals. Proceedings of the National Academy of Sciences , 108:2312–2315, 2011. [1] G.V.N. Powell. Experimental analysis of the social value of flocking by starlings (Sturnus vulgaris) in relation to predation and foraging. Animal Behaviour , 22:501–505, 1974.