RoboSquirrel Update

Back in March I introduced Robo Squirrel, a robotic California ground squirrel developed by researchers at the University of California Davis and UC San Diego. The robot was designed to help researchers learn about the predator-prey interactions between rattlesnakes and ground squirrels.

Robo Squirrel in the lab

The specific questions that the scientists hope to address involve two actions that squirrels take when they are confronted by a rattlesnake: tail flagging, or waving of the tail while facing the snake; and heating up of the tail, which is done by increasing the blood flow. By facing down a rattler while simultaneously performing these two actions, a ground squirrel is somehow able to confuse or frustrate a threatening snake and cause the predator to back off. The researchers want to know if either of these actions is more important, or if it is a combination of the two that is effective in fending off a snake attack.

A real California ground squirrel

The researchers place Robo Squirrel in a spot where they have observed rattlesnakes nearby. When it is threatened by a rattler, they can make it wave its tail, heat up its tail, or do both. What they have found so far it that it seems to be the heating of the tail that is most important. The snakes can "see" the infrared energy emitted by the heating of the tail, and in most cases this seems to frustrate them into backing off. The tail flagging is an additional step that the squirrels take to emphasize an aggressive stance toward the snake.

The squirrels will only use these actions if there are baby or juvenile squirrels nearby. The snakes will most often attack baby or juvenile squirrels rather than adults. The adult squirrels have resistance to snake venom, can usually survive a bite, and may hurt or even kill a rattlesnake in a fight. The tail heating and flagging is a signal to the snake that it has been seen, the squirrel knows it is there, and most often the snake would rather back off and find food somewhere else rather than fight.