Immobile defence of a frog distracts attention of approaching predators to other prey

Escape theories predict that animals remaining motionless after being detected by a predator are less successful in predation avoidance because it simply allows the predator to come closer. Nonetheless, even in such a situation, some animals often remain motionless for a while before escaping. We hypothesized that this non-immediate escape response increases the survivorship of the prey by distracting the predator’s attention to another nearby prey that indifferently comes into the visual field of the predator that is carefully and inconspicuously approaching the former prey. Staged encounter experiments using frogs and snakes as prey and predator, respectively, yielded the results that support this hypothesis. Considering the density of frogs in the field, this phenomenon is feasible under natural conditions. Therefore, remaining motionless after being detected by predator could be an effective choice for prey to avoid predation under a certain condition.