Hugh Pickens writes writes "Alasdair Wilkins writes that when a squirrel encounters a rattlesnake in the wild, it does something very peculiar to survive its brush with the predator — something is so peculiar that scientists are building robotic squirrels just to try to understand the behavior. A live squirrel does two things when it sees a rattlesnake. It starts moving its tail in a flagging motion and actually heats up the temperature of its tail. Because rattlesnakes can see in the infrared wavelengths, they should be able to see both the tail move and heat up. The question is which of these two signals is important and just what message it's supposed to send to the rattlesnake. To that end, engineers at UC Davis have built robosquirrels, which allow the biologists to simulate the two squirrel behaviors one a time and the research so far suggests it's the heated tail, not the flagging motion, that the snake responds to, making it one of the first known examples of infrared communication between two distinct species. "Snakes will rarely strike at a flagging adult squirrel — and if they do they almost always miss," says Rulon Clark, assistant professor of biology at San Diego State University and an expert on snake behavior. "In some cases, it seems the rattlesnakes just decide it's best to cut their losses after dealing with these confusing critters," adds Wilkins, "as sometimes the snakes just leave the area completely after encountering these flagging, tail-heating squirrels.""