As Rundus and his colleagues wrote in Proceedings of the National Academy of Sciences, the rattlesnakes were much more afraid of the robotic squirrel when its tail was heated.
Rundus considers this a marvelous story of evolution, where a special ability in rattlesnakes (sensing infrared radiation) triggered evolutionary changes in squirrels that they employ against a specific predator.
Squirrels probably had some ability to heat up their tails long ago, but it might not have been fully employable. But over time, it became the kind of ability that would better maintain the species through generations.
"Squirrels probably tail flagged without this component first," Rundus says. "But the groundwork was there for them to increase the temperature, and over time squirrels' ability to do it was probably selected for, and probably increased in frequency and power throughout the population."
He is also fascinated by the subtle and unexpected ways other species in nature can communicate.
|The rattlesnake is more afraid of the robot squirrel (lower left) when its tail is heated.|
image: Aaron Rundus
"One of the most interesting things is the reminder that when we look at animals and understand how they work, we need to take into account the perceptual working domains of the animals, and not be constrained by our own human perceptual biases," he says. "When you do that, you can find some really interesting phenomena."
Rundus' paper was published in the August 13-17, 2007 Online Early Edition of PNAS, and was funded by the American Society of Mammalogists, Sigma Xi, the Animal Behavior Society, American Museum of Natural History, and the Chicago Herpetological Society. The study earned Rundus an award for best student paper from the Animal Behavior Society.