The snow, and the tracks, are (temporarily?) gone from our deck. The tracks were created by one or more squirrels and by Franco, our rescue dog border collie mix, ardently chasing said rodents from the area. Franco does this, I believe, because keeping the deck free from squirrels (and tigers for that matter) gives him a sense of accomplishment. We are lacking sheep, goats, chickens, ducks and any other herd or flock animals on which Franco can unleash his herding instincts. Frustrated herding instincts make life highly unsatisfactory for dogs like Franco. The other satisfaction Franco gets chasing squirrels from the deck has to do with allowing more birds to the feeder when the squirrels aren't dominating them. Franco enjoys watching the birds almost as much as he enjoys barking at squirrels. I've noticed recently that actual squirrels don't have to be present for Franco to chase them away. He often demands the opportunity to charge, barking loudly, through the walkout door and onto the deck whether I (or he for that matter) can see squirrels or not. I guess this comes under the heading of preventative squirrel chasing. Maybe he can smell them through the door? No, I'm not buying that. He likes the chance to feel dominant, that he's done something worthwhile. No one in the family lets him herd them. A guy needs some outlet for his desire to create order in the world. Don't we all?