Do all Members of a Swarm Suffer the same Predation?1

Using three‐spined sticklebacks (Gasterosteus aculeatus) as predators and water fleas (Daphnia magna) as prey, experiments were conducted to investigate whether different swarm regions were differentially preyed upon. The specific location of a region within the swarm, its density, and the motivational state of the predator all influenced the risk of predation. As stragglers were more often attacked than any portion of a swarm itself, natural selection favours all individual swarm members, although differentially.