What is the main conflict in The Tracker by Tom Brown?

As a young man, Tom Brown, Junior, loves to be out in the woods. He especially loves finding clues to what is going on with the wildlife in the woods. He is blessed with the perfect opportunity to learn everything he wants when he makes a best friend in grade school, a boy named Rick who has a wonderful grandfather called Stalking Wolf, an Apache Indian. Rick and Tom both call Stalking Wolf "Grandfather," and the elder has a wonderful way of teaching the boys how to understand the woods, and how to survive and even thrive in conditions that many would call hostile.