A new study from the University of Bristol used robots to investigate how predators react to unpredictable movements from prey – testing a long-held theory that erratic movements can help animals escape an aggressor. 

The team from Bristol’s School of Biological Sciences studied how blue acara cichlids responded to robotic prey that was programmed to move in certain patterns to escape, while monitoring the predators’ reaction to random versus predictable movements. 

“Using robotic prey allowed us to present individual predators with one of two prey escape strategies: ‘predictable’ prey which repeatedly escaped in the same direction from one interaction with the predator to the next, or ‘unpredictable’ prey which escaped in random directions,” said lead author Dr Andrew Szopa-Comley.

The results disproved the theory. Instead demonstrating how predators can adapt their movements to neutralize their preys’ random pathways, accelerating in the later stages of their hunt to compensate for time lost in assessing the bot’s movements. 

“Our results suggest that the predators in our study were able to overcome the potential downsides of facing prey which behave unpredictably,” said senior author Dr. Christos Ioannou. “From the prey’s point of view, this raises the question of whether unpredictable behavior is as widely beneficial as was originally thought.”

Results from the study were published in June in the science journal PNAS.