For those that don’t know, a coyote roller is a 4-foot aluminum roller that is designed to stop animals from scaling the top of a fence. The way that it works is when a coyote or other animal climbs to the top of a fence, the aluminum roller spins when they try and get their footing. When the roller spins they are unable to hold on and harmlessly fall to the ground.
Why do dogs jump up? A plausible explanation arises from their ways of communicating with each other. A puppy greeting an adult dog often licks the adult’s muzzle -- a polite, deferential behavior. Dogs, of course, descend from wolves, among whom muzzle-licking is how pups get the grownups to regurgitate food for them. Domestic dogs rarely nourish puppies this way, but muzzle-licking has survived, maybe because deferential behaviors are handy for a social animal. Think of humans saying “No, after you.” Muzzle-licking is also an appeasement behavior -- something you trot out to de-escalate a fight. A human might lift up his hands, palms toward the person he’s arguing with.