Collective Motion due to escape and pursuit response
  Recent studies suggest that non-cooperative behavior such as cannibalism may also be a driving mechanism of collective motion. Motivated by these novel results we introduce a simple model of Brownian particles interacting by pursuit and escape interactions. We show the onset of collective motion due to escape and pursuit response of individuals and demonstrate how experimentally accessible macroscopic observables depend strongly on the ratio of the escape and pursuit strength. We analyze the different impact of the escape and pursuit response on the motion statistics and determine the scaling of the migration speed with model parameters. 
Pawel Romanczuk, Iain D. Couzin, Lutz Schimansky-Geier