A large yellow sign that reads duck crossing stands on the edge of a busy road near Rochester, N.Y.  It is a phenomenon to watch.  At any given time several families of geese can decide to stroll to the other side.  Several minutes can go by before the last goose has safely crossed.   They bring lines of cars to a standing halt.  No one honks a horn, no one yells, no one pushes forward,  no one interrupts the family of geese.  The drivers in their cars have slowed down and enjoyed the parade.