Robot lizards solve predator-prey riddle

Scientists from UNSW believe they have solved the perennial puzzle of what deters some wild predators from certain species of prey.

Scientists from UNSW believe they have solved the perennial puzzle of what deters some wild predators from certain species of prey. Picture: Katrina Bridgeford.

In a world first experiment, scientists from UNSW believe they have solved the perennial puzzle of what stops some wild predators from certain species of prey which could easily end up on their dinner plate.

Beginning in 2018, evolutionary ecologist Terry Ord led a research team of scientists to Borneo in an attempt to answer the question, with robotic lizards providing the unlikely key.

“On the face of it a predator should really go for anything”, Dr Ord said. “But at the heart of our research was this paradox of why predators avoid conspicuous-looking prey, which could easily be objects of predation, and go for something potentially harder to find and less obvious.”

For more than three months, Dr Ord’s research team worked to manufacture and program robotic Draco lizards – a variety of lizard found across South East Asia and comparable to the Australian skink.

The team programmed thousands of robots which could perform different actions, sounds and gestures that Dr Ord described as both “conspicuous or cryptic behaviours”.

“Once we finished the manufacturing stages we covered the lizards in a plasticine mould, so we could easily detect the species of predator that attacked them and then we deployed them in the trees and the wild in Borneo.”

Over the course of four field trips, Dr Ord said it became clear that predators – such as snakes, monitor lizards, large rats, birds, cats – were avoiding prey that looked unusual, including prey that obviously stood out in their environment.

“Instead what we found was that cryptic robotic prey (those who camouflaged into the environment and did not stand out) were frequently attacked because these prey behaved and looked more familiar to predators.”

“The classic expectation is that standing out in the environment increases predation … But many prey species are not cryptic, and extravagance seems to be the norm for many animals that rely on conspicuous communication for finding a mate and for reproduction.”

Dr Ord argues that predators are innately conservative by nature, especially when it comes to considering what they want to eat, and observing anything they perceive as unfamiliar or unusual.

“There is something fascinating in their genetic makeup that tells them they should avoid certain colours, sounds and features, which we think would make them easy picking, but actually have the exact opposite effect.”

The group’s research findings have now been published in the academic journal, Proceedings of the Royal Society B.