When a rattlesnake shakes its tail, it’s sending a clear message. “It’s shouting, ‘I’m here! Don’t come closer!’” says Boris Chagnaud, a biologist at the University of Graz in Austria. He recently discovered another way the snake’s rattle scares off animals.
When a potential threat approaches, a rattlesnake will gradually increase the number of times it rattles per second. That tells the animal how close it’s getting to the snake. Chagnaud found that when a predator gets too close, the rattling sound suddenly jumps to a much higher number of rattles per second. To learn more about this behavior, the scientist had volunteers wear virtual reality headsets that simulated walking through a field containing invisible virtual rattlesnakes. The participants were asked to press a button when they thought they were about 1 meter (3 feet) from a “snake” based on its rattling sound.
Scientists found that when the number of rattles per second suddenly increased, volunteers often thought a snake was closer than it actually was. Some estimates were off by as much as 3 m (10 ft). Chagnaud believes this trick is another way rattlesnakes keep predators at bay.