Who dares, benefits: predator approach behaviour in the guppy (Poecilia reticulata) deters predator pursuit

Animals commonly approach (or inspect) potential predators at a distance, a practice which is inherently risky and apparently paradoxical. Individuals which dare inspect predators, and who are therefore willing to accept the associated costs, must gain additional fitness benefits from doing so which non-inspectors do not. Here, we report a direct fitness benefit for predator inspection behaviour in the form of a reduced risk of predation on inspectors compared with non-inspectors. Using guppies (Poecilia reticulata) and blue acara cichlid fish (Aequidens pulcher) as a model prey-predator system, we demonstrate experimentally that the predators were significantly less attentative to, and less likely to attack and kill, guppies which inspected them than those which did not. They were thus more likely to abort an initial approach towards an inspecting guppy than a non-inspecting one, and as a consequence, inspectors incurred a significantly lower risk of attack and death than non-inspectors when approached by the predator. Our results constitute strong evidence for a predator pursuit-deterrence function of predator inspection behaviour in the guppy, and also have implications for the conditions necessary for the evolution of predator approach behaviour as a cooperative strategy in prey.