This Rattlesnake Dares You to Call Its Bluff

Scientists designed a virtual reality experiment to understand just how tricky rattlesnakes can be.

The Western diamondback rattlesnake is a master of nonverbal communication. It need only shake the rattle on its tail to send a crystal clear message: “Hey. I’m sitting here. Don’t step on me because I’m going to bite you,” said Boris Chagnaud, a biologist at the University of Graz in Austria. But the rattlesnake has another, wilier trick up its tail. As it perceives a potential threat coming closer, the rattlesnake will sharply increase the speed of its rattle, accelerating from da … da … da … to dadada. Dr. Chagnaud compares the acoustic warnings to a car’s backup beeper, which will beep more as the back of your car approaches an object. This uptick tricks unsuspecting humans into believing the snake is closer than it actually is, according to a paper by Dr. Chagnaud and colleagues published in the journal Current Biology on Thursday. Scientists knew that rattlesnakes often change their rattling noises, but no one quite knew why. Matthew Rowe, a biologist at the University of Oklahoma who was not involved with the research, said he had witnessed this rattling trick hundreds of times but never questioned what the signal might be communicating to the snake’s enemies. “That’s embarrassing for me,” he said.