Thursday, August 16, 2007

Squirrels and Rattlesnakes

First it was the squirrels attacking women's legs in Chicago. Then it was squirrels spying on Iran for the West (and getting arrested for their deeds). Now it's even worse.

Scientific American reported Tuesday that squirrels even attack rattlesnakes.

Seemingly skittish, adult squirrels are fearsome defenders. Aided by a natural blood protein that counteracts snake venom, they may approach within inches of a threatening snake, throwing dirt with their front paws and even biting or swiping at the snake's tail, which can leave a nasty infection. "Sometimes you feel a little bad for these rattlesnakes," says [behavioral biologist Aaron Rundus of the University of Nebraska–Lincoln School of Biological Sciences], who conducted the experiments while working toward his PhD at the University of California, Davis, with adviser Donald Owings.

But that's not the interesting part. The squirrels have super-powered tails.

Squirrels are not as helpless as they may seem when confronted by rattlesnakes eager to make dinner of their pups. A new study reveals one of their most powerful tactics: the rodents heat their bushy tails and wave them back and forth to warn infrared-sensitive snakes they will not get fast food.

Infrared video showed that California ground squirrels' tails warmed by several degrees, up to 28 degrees Celsius (82 degrees Fahrenheit), when threatened by northern Pacific rattlesnakes, which detect the infrared glow from small mammals using so-called pit organs in their noses. But no heating occurred while the rodents defended against gopher snakes, which lack such heat seekers, according to a report in Proceedings of the National Academy of Sciences USA.

Squirrels and snakes have coexisted for more than a million years in California, matching one another step for step in their evolutionary struggle for survival, he adds. When snakes developed venomous bites, squirrels evolved antivenom. The researchers say squirrels may distinguish infrared-sensitive rattlesnakes from gopher snakes and other predators based on rattlers' distinct odor and sound.

Sadly for squirrel lovers (but comforting to viper devotees), Rundus notes that these weapons are not perfectly effective: Earlier studies have found that a rattlesnake's diet is 70 percent squirrel pup.

Such a shame...

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