Death imagery
On the mountain, things are more dangerous than at home among one's community. For Sam, death imagery seems constantly around him. When he finds a falcon, he names it Frightful. The animal helps him kill. Before long, he's an established, skillful hunter, killing animals on the mountain for his own animal survival. The death is a constant reminder of the true stakes of survival, which are his own life and death.
The mountain wilderness
The woodland mountains are the domain of incredible strain and discomfort. Survival involves injury and healing, hunting, gathering, creating solutions to problems that don't exist in society, like how to replace clothes so far away from the nearest human. For this, he resorts to wearing animal pelts. Once this happens, he is thoroughly indoctrinated in mountain life, and has become part of the wild imagery himself.
The portrait of the young person
The novel can be seen as narrative imagery, helping the reader form a picture of the life a young person. Sam is truly brave, so the portrait is formed in full splendor. Instead of a season of moody rebellion, he goes the whole nine yards and just leaves. He straight up runs away, taking life on in the most direct way he can imagine. He survives, by the skin of his teeth, and re-enters his community. It is the journey of bildungsroman.
Winter imagery
For Sam, the winter is the time of intense challenge and isolation. He is absolutely at risk, because any sudden change in weather could lead him to die in the woods, literally. In the early winter, there are still predators, which are most specifically suited for that weather than him, symbolizing a kind of natural menacing. But, in the winter, he receives visitors, Matt, and Tom. So the winter is also the domain of surreal life, where anything can happen, from death to random visits from strangers.
