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November 3, 2005

Rodent Radiation: Squirrels Get Sassy

Remember those nature shows that use night vision to illustrate how owls locate prey at night? While owls have good vision in low light, they only see in black and white and they don't have thermal vision, instead they rely more on sound to find prey.

Pit vipers like rattlesnakes have specialized thermoreceptors, heat-sensitive organs located on the head to detect prey. Recently, biologists discovered a critter that purposefully used infrared against the rattlesnake - just to rattle it's chain!

Ground squirrels are the first animals reported to broadcast an infrared signal, and the message seems to be "Nyah, nyah."

When adult California ground squirrels discover a lurking rattlesnake, they often harass it... They dash into its striking range, kick sand at the snake, nip at its tail, and whip their own tails back and forth ... A snake subjected to such vexations sometimes slithers off to lurk somewhere else.

Infrared videos show that ground squirrels' tails, which are generally cooler than the bodies, heat up during a bout of rattlesnake baiting... Rattlesnakes have infrared sensors inside little pits below their eyes, and Rundus proposes that the tail's heat enhances the harassment display.

In contrast, the ground squirrel tails didn't warm appreciably during similar taunting of a gopher snake. This predator doesn't have infrared sensors.

More at: Hot Bother: Ground squirrels taunt in infrared

Posted by sorsha at November 3, 2005 12:39 AM