Piping Plovers Across from Charles Island   I followed as far as the tombolo but nothing could convince me to walk where the earth was so willing to give itself up to sea.   Cobble-grey waves shrugged their habitual tide. You in a green parka seemed the only promise of season shrinking to a seedpit at the end of the sandbar’s raised curve— an abbreviation of the ocean’s coming in, going out and only cross-able two hours each day. Waiting behind   among the pale driftwood where a tangle of seaweed lashed the closing eye of beach berm, I heard…