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Realistic Robots Provide Clues to Lizard Interaction

Biologist Dave Clark and his students successfully employed an interactive robot that responds to the immediate actions of a live lizard in their habitat on the Galapagos Islands.

A real lizard encounters a life-like robot in the natural habitat of the Galapagos Islands.A real lizard encounters a life-like robot in the natural habitat of the Galapagos Islands.

Animal robots have become effective tools in the study of animal communication. For several years, Alma College biologist Dave Clark has used realistic-looking robots in his research on the Galapagos lava lizard, a small ground lizard unique to the islands.

Until now, the robots were programmed to act in a predetermined fashion unaffected by the response of a real lizard. In his newest study, Clark and his students successfully employed an interactive robot that responds to the immediate actions of a live lizard.

“Our research confirms that scientists can use robotic stimuli to interact with these animals, to communicate with them and even manipulate their behavior, which in turn furthers our understanding of how lava lizards respond to each other in their natural habitat,” says Clark.

An example of lava lizard behavior is observed in male contests for access to reproductive females. In these confrontations, the males assess each other while avoiding dangerous fighting that can lead to injury. The males perform head-bobbing displays where the lizards respond to each other in reciprocal fashion.

Dynamic Back-and-Forth Encounters

“In our study we used a realistic lizard robot as a stand-in for a contestant in a simulated encounter,” says Clark, who conducted his study in natural habitat on the Galapagos Islands. “The robot responded to the live lizard depending on what the live lizard was doing. There was a dynamic back-and-forth.”

Clark observed how the lizard reacted if the robot immediately responded or delayed responded to a head bob by the real lizard.

“We found that an immediate response by the robot stimulated the lizard to display significantly more often than when the robot’s response was delayed by 30 seconds,” he says.

“If the robot’s response was immediate, the live lizard would escalate its response — as the lizard responds, the robot responds — a feedback loop. If the response was delayed by 30 seconds, the live lizard slowly decreased its response time. The lizard didn’t see a delayed response as a real threat.”

First Interactive Robot Playback

The interactions were recorded by video using two cameras — one focusing on the robot lizard, the other on the live lizard — for analysis.

The adult male-sized robot bodies were hand-carved from wood and secured with eyelets to a pushrod and servomotor that controlled the robot displays. Latex limbs and tail were glued to the wooden body, which was covered with a high-resolution photo, scaled to life-sized proportions, of an adult male. The robots are connected to a computer that controls the actions of the robot.

Recent graduate Michaela Austin and senior Isabella Centurione assisted Clark with his research. Austin traveled to the Galapagos Islands with the research team and helped run the field experiments. Centurione was responsible for scoring and analyzing the videos.

Clark’s research has been accepted for publication in the scientific journal Behavioral Ecology and Sociobiology. Read more.

“To our knowledge this is the first interactive robot ‘playback’ experiment with lizards,” says Clark, the Charles A. Dana Professor of Biology. “Future research will further explore the ‘rules’ underlying display behavior in lizard contests.”

Story published on September 05, 2019