SEATTLE - The odor of bobcat urine, if you ever get a chance to take a whiff, is unforgettable -- like rotten meat combined with sweat, with something indescribably feral underlying it. To humans, it's just nose-wrinklingly disgusting.
But to mice, it smells like one thing: fear.
Rodents respond instinctually to this trace of their natural predator. Even those mice raised in the lab, which have never been exposed to bobcats -- or cats of any sort -- respond to it.