Final scene from the book (spoilers)

I know this is the wrong forum but I just finished watching the movie and was reminded about the sinking of the Pequod. As the ship goes down Tashtego is still nailing a flag to the mast and he catches a hawk with the hammer and drags it down with the ship.
This always puzzled me. I suppose it is allegorical but really don't know what it means. Is there a biblical significance?