What is that at the end of the driveway?

On the way down the driveway for the morning walk Sparky started barking. He had never done this before and there were no dogs in sight, maybe it was the big garbage can at the end of the driveway. I quickly worked on correcting him and by the time we passed the next door neighbors garbage can, it had resolved. He was introduced to a new word today, "QUIET".