Fish bones walked the waves off Hatteras.
And there were other signs
That Death wooed us, by water, wooed us
By land: among the pines
An unculred cottonmouth that rolled on moss
Reared in the polluted air.
Birth, not death, is the hard loss.
I know. I also left a skin there.
In this poem there are a few things I looked up to help understand the meaning. Hatteras is the first. There are many accounts of ships being caught in unfavorable winds and not being able to round Cape Point. Surfmen with the Lifesaving Service maintained a close watch over the ships in the doldrums. It would spell certain disaster should the winds turn unfavorable and drive them closer to shore. One such watch reported over 100 vessels (http://www.hatteras-nc.com/history/hatteras-village-history.shtml). The second I wanted to look up was cottonmouth. The cottonmouth is a type of snake found in swamps in the United States. This make sense towards the line "An uncurled cottonmouth that rolled on moss".
From this poem and the definitions provided I see it meaning that this poem is about changes. That both life and death bring changes to the world, probably more specifically the United States since the places and the animals referred to are only found in the US. I also think that the writer of this poem is referring himself as the snake from the line "I know. I also left a skin there." I think that he means skin as in shed skin like a snake. The snake visited this place of Hatteras and was overwhelmed with death and pollution. Birth is the hard loss because this place is so disgusted with things like death and pollution.