Collective animal behaviour
1.3 A third possibility is the ‘encounter dilution’ effect. Hamilton proposed that the aggregation of animals was due to a “selfish” avoidance of a predator, and was a form of cover-seeking. Another formulation of the theory was combining avoidance and dilution. It was suggested that potential prey might benefit by living together since a predator is less likely to chance upon a single group than a scattered distribution. About attack, it was thought a predator is less likely to eat a particular animal when a greater number of individuals are present. In sum, an individual has an advantage if it is in the larger of two groups (assuming that the probability of detection and attack does not increase disproportionately with the size of the group).