Foraging and Evading Predators: The Effect of Predator Species on a Behavioural Trade-Off by a Lotic Mayfly

We performed laboratory experiments to test the hypothesis that predator species influenced a forager's trade-off between predation risk and food reward. Larvae of the stream mayfly, Baetis tricaudatus Dodds, were provided with simultaneous access to feeding patches in laboratory streams that differed in predation risk (safe, risky) and food reward (low, high). Predation risk was imposed using either: (1) a fish predator, the longnose dace, Rhinichthys cataractae (Valenciennes), (2) a stonefly predator, Claassenia sabulosa (Banks), and (3) both predators is risky patches at the same time. We hypothesized that predator species would influence the behavioural trade-off between predation risk and food reward because mortality risk on Baetis from Rhinichthys exceeds that from Claassenia