Aug. 13, 2007 — Like Wile E. Coyote's hapless quest to catch the Roadrunner, rattlesnakes have attempted to catch California ground squirrels for well over a million years, and now scientists know one reason why the squirrels usually win.
Their tails freak out the snakes, researchers report in this week's Proceedings of the National Academy of Sciences.
The secret is the squirrel's ability to heat up its tail before flicking it in admonishment at a threatening rattlesnake, the researchers believe. For the first time, the scientists captured the phenomenon using a special infrared camera.
Lead author Aaron Rundus, who conducted the research while he was a member of the Animal Behavior Graduate Group at the University of California, Davis, explained to Discovery News that rattlesnakes have pit organs that are ultra-sensitive to infrared. This form of light consists of electromagnetic waves, just below the range of visible light, that correspond to radiated heat.
"When combined with other squirrel harassment activities, the squirrel tail flagging puts rattlesnakes on the defensive," Rundus said.
Squirrels will chatter with their big teeth and even "throw sand and loose pebbles at the snakes," he said. At the same time, the squirrels wave hot, glowing tails puffed out to make themselves look enormous to the snakes.
Since squirrels can neutralize rattlesnake venom, such battles usually occur between mother squirrels and rattlesnakes targeting pups, which have not yet developed the immunity.
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