The video was made by Rulon Clark, a biology professor at San Diego State who is trying to determine how squirrels and rattlesnakes communicate in the wild. The rattlers don’t attack adult squirrels, which are immune to their venom. But in the spring and summer months, they love to dine on infant squirrels. Hence the need for squirrel vigilance.
When a squirrel thinks a hungry rattlesnake is nearby, it doesn’t run away. Instead, it stands its ground, hurling pebbles and dirt at the would-be predator and wagging its raised tail in a menacing way. It keeps the snakes at bay, but scientists aren’t entirely sure why.
In a 2007 report in Proceedings of the National Academy of Sciences, UC Davis researchers explored the theory that snakes detect the infrared signal of the wagging tail and mistake it for a larger, more intimidating creature. In a staged confrontation, the tail temperature shot up by 12 degrees, which made a bigger impression on a snake.
Then came “robo-squirrel,” a mechanical taxidermy squirrel with heating tubes in the tail that can be remotely controlled. When matched against a real snake, the robo-squirrel was a formidable foe. As its tail heated up, the snake shifted from an offensive posture to a defensive coil, according to the 2007 study.
Robo-squirrel has since gone through several modifications. In the video, robo-squirrel got close to a wild snake and was attacked when its tail was still. In another take, the tail moved back and forth. The snake remained hidden in tall grass.