Tadpole behavioural responses to predation are governed by cost-benefit judgments, which should conform to the expectations of the economic model of predator escape. This study documents the behaviour of tadpoles (Crinia sp.) in natural ephemeral streams in Walpole, Western Australia in response to a stimulated aerial predation event. We found that smaller tadpoles tended to rely on immobility in response to tactile stimulation, whereas larger tadpoles tended to respond with a burst of movement, consistent with economic predictions. It was also found that distance swum in response to a threat does not correlate with tadpole size, but varies between individual sites. This may indicate that where a movement response was elicited, it is not intended to put a greater distance between prey and predator, but to break free from a potential predator. Utilization of crypsis was not unequivocally demonstrated, but cannot be discounted as a predator avoidance tactic in these habitats. Our results support the economic model for predator escape, thus confirming it applicability to tadpoles in ephemeral habitats, when the unique physical and energetic constraints are considered.