I wrote this several years ago:

There is nothing more unsettling than a dead squirrel. When we see a dead opossum we yawn (the damn things move so slow, it’s a wonder they are not extinct), but when we see a dead squirrel we are spooked, because no other city creature has the squirrel’s agility. They can leap from branch to branch without hesitation, and race up tree trunks with the same speed and ease that powerful mammals race down sharp slopes. Squirrels mock gravity, whose force seems to have no influence on their daily gymnastics through gardens and parks. This is why a dead squirrel, a squirrel that is not leaping, climbing, scurrying, defying the laws of gravity, is unnatural, a freak of nature. Indeed, a lifeless squirrel has about it the aspect of an omen.