writes "A recent article in PNAS reveals a novel mode of communication between ground squirrels and rattlesnakes. Apparantly, squirrels can scare off snakes by employing a technique called "tail flagging" — frenetic back and forth waving of the tail, "harassing" the snake. Using infrared cameras, scientist have discovered that when encountering infrared sensitive rattle snakes, the tail also heats up, putting even more fear into the snake. Experiments using a robotic squirrel (!) confirms this. Interestingly, the squirrel can discriminate between infrared sensitive and non-sensitive snakes, only heating up the tail if it encounters the former kind.
Only the abstract is availabe for non-subscribers, but here is a summary of the article along with some nice pics and movies."