Squirrels' secret weapon? Eau de rattlesnake

To protect themselves from predators, squirrels scent themselves with rattlesnake. From an older article in USAToday:

"Recently, two squirrel species were discovered to anoint their bodies with rattlesnake scent as a means of concealing their odour from these chemosensory predators," begins the study in the current Journal of Evolutionary Biology. It was written by a team led by Barbara Clucas of the University of Washington in Seattle. The two ground squirrel species chew up shed snake skins and lick their fur to acquire the scent of their predators. In the study, Clucas and colleagues track back the origins of protective snake scents on squirrels, first by checking the popularity of such chemical disguises among 11 squirrel species, including two kinds of chipmunk. In field trials, the team checked the squirrels fondness for rattlesnake, weasel (another predator) and deer (a non-predator included as a test) stinks. The team also tested the fondness of 15 wild North Pacific rattlesnakes for mice burrows that did and didn't smell of their kind.

The link to the actual study abstract can be found here.