Brian makes a food shelf so that he will have a place to store his food where it will be safe. He has learned from experience that if he leaves his food in an accessible area, wild animals will come and take it away before he can use it. When Brian remakes his shelter to better suit his needs, he looks for a place where he can store his food, a place that is "high, somehow, high and safe." He discovers a small ledge, a "natural storage place, unreachable to animals" in the rock face above the door of the shelter. It is definitely high enough so that the animals will not be able to reach it; unfortunately, it is out of Brian's reach as well.
Brian solves this problem by finding a dead pine "with many small branches still sticking out." With his hatchet, he chops off the branches so that they protrude only four or five inches all along the log. When he props the pine up in front of his food shelf, he is satisfied to discover that it serves as a makeshift ladder; when Brian needs to get a food item down from his shelf, he can set the "ladder" up and climb up to fetch it.
Brian's food shelf is covered with old bird manure, and he carefully scrapes it clean with sticks. He then fashions a door for the small opening to the shelter which lies below the food shelf, and allows himself to enjoy a moment of satisfaction when he stands back to look at how skillfully he has fashioned his shelter to suit his needs. Brian then begins to think about what kinds of foods will last, and would be practical to keep stored up on his shelf (Chapter 14).
Brian discovered that leaving food accessible to the animals and other forces of nature was foolish. With that fact in mind, he determined to build himself a storage spot for the food so that animals would be unable to reach his stash.
This activity also caused him to think about what types of foods would be non-perishable, or those that would last a very long time in storage. Brian also has to construct a method to reach his high shelf, and creates a ladder from the nature around him (pine trees, etc.). This scene shows how Brian's approach to survival is evolving.