How does the author use foreshadowing in Slake's Limbo?

In Chapter One, the dream of the bird symbolizes the angst inside of Slake. He has no one to love him. He is tortured all the time. To him, the world is hostile and against him. The bird is supposed to be a peaceful bird who sits on Slake's windowsill. But even the bird is hostile as he enters Slake's mouth. Slake swallows him and the bird pecks at his ribs. This symbolizes that angst and hostility gnaw away at Slake. It is a constant feeling for him. He does not know how to be happy or feel at peace. Even when he is asleep, the bird brings hostility to his dreams. This foreshadows that Slake will not get rid of the bird until he finds his inner peace.