I was walking through the neighborhood one afternoon when, on turning a corner, I nearly tripped over a gray squirrel that was sitting in the middle of the sidewalk, eating a nut. Startled by my sudden appearance, the squirrel dashed out to the road right in front of an oncoming car.
You don't get to be one of the most widely disseminated mammals in the world equally at home in the woods, a suburban backyard or any city "green space" bigger than a mousepad if you're crushed by every Acme anvil that happens to drop your way.
"When people call me squirrely," said John L. Koprowski, a squirrel expert and professor of wildlife conservation and management at the University of Arizona, "I am flattered by the term."
The Eastern gray tree squirrel, or Sciurus carolinensis, has been so spectacularly successful that it is often considered a pest. The International Union for Conservation of Nature includes the squirrel on its list of the top 100 invasive species. The British and Italians hate gray squirrels for outcompeting their beloved native red squirrels. Manhattanites hate gray squirrels for reminding them of pigeons, and that goes for the black, brown and latte squirrel morphs, too.
Yet researchers who study gray squirrels argue that their subject is far more compelling than most people realize, and that behind the squirrel's success lies a phenomenal elasticity of body, brain and behavior. Squirrels can leap a span 10 times the length of their body, roughly double what the best human long jumper can manage. They can rotate their ankles 180 degrees, and so keep a grip while climbing no matter which way they're facing. Squirrels can learn by watching others cross-phyletically, if need be. In their book "Squirrels: The Animal Answer Guide," Richard W. Thorington Jr. and Katie Ferrell of the Smithsonian Institution described the safe-pedestrian approach of a gray squirrel eager to traverse a busy avenue near the White House. The squirrel waited on the grass near a crosswalk until people began to cross the street, said the authors, "and then it crossed the street behind them."
In the acuity of their visual system, the sensitivity and deftness with which they can manipulate objects, their sociability, chattiness and willingness to deceive, squirrels turn out to be surprisingly similar to primates.