Brinkmanship and the sensory-motor limits of pursuit predation
Predators routinely fail to capture prey despite being larger, faster, and more powerful. Half a century ago, theory predicted that prey could evade biomechanically superior predators using brinkmanship, delaying evasive maneuvers until the last possible instant, but this hypothesis has never been tested in the wild. Here, using more than 2,000 hours of high-speed stereo-camera recordings of predator and prey coral reef fishes, we show that prey successfully evade 97% of attacks. However, contrary to the standard explanation that prey evade through superior maneuverability, we find that prey evade by exploiting their predator's sensory-motor delay - the interval between a stimulus reaching the predator and the onset of the predator's motor response. Although predators partially compensate for this by forecasting prey position during interception steering, prey consistently time evasive maneuvers within a brief window just tens of milliseconds before collision, within which no viable predator trajectory can intercept them. Prey do not, however, turn at the time that maximizes miss distance, but slightly later, a bias that makes escape robust to variability in their own response timing. These findings reveal how temporal delays in perception and action place fundamental limits on the outcome of predator-prey interactions, and show that prey can exploit delays in a way that approaches the theoretical limit of escape performance.