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.
When a squirrel thinks a rattlesnake is nearby, rather than running away, it will raise its tail, heat it up, and wag it. Scientists call this "flagging behavior."
It seems that the rattlesnake is less likely to strike a squirrel that is exhibiting flagging behavior, but scientists are not entirely sure why.
One hypothesis: The flagging behavior may indicate what Clark calls "squirrel vigilence, or squirrel awareness," which might tell the snake that it no longer has the element of surprise on its side. But is it the heating of the tail that the snake is responding to, or the back and forth movement? Or is there something else going on?
"A lot of work is done on prey, but predators tend to be harder to study," he said. "We know a lot about the sender of the signal, but we don't know much about the receiver of the signal."
Enter robosquirrel. Designed by Sanjay Joshi, a professor of mechanical and aerospace engineering, to help scientists learn about the interaction between squirrels and rattlesnakes, robosquirrel has gone through several iterations since it first met a rattlesnake in a UC Davis lab in 2005.
Robosquirrel is basially a mechanical stuffed squirrel with heating wires in its body and heating tubes in the tail that are connected to a temperature control system beneath the robot. Thanks to a custom controller board, scientists can control whether it wags its tail and how hot the tail and the body get.
In its current iteration, it runs along a plastic track so that scientists can introduce it to a rattlesnake without having to get too close to the snake.
As you can see in the video below, it fooled the snake.