Now that autumn approached, what did Sam observe about the animals in My Side of the Mountain?

This happens in the chapter "In Which The Autumn Provides Food and Loneliness." Sam notices that mice are harvesting the grass seeds. Squirrels and chipmunks collect all sorts of nuts and hide them. The birds begin to gather together in order to start migrating south. The Baron, the weasel that Sam sees frequently, begins to look "moldy." Sam realizes that the animal is changing into his winter fur. He takes his cues from the wild ones. Seeing the animals prepare for food storage and for staying warm during the coldest months, forces Sam to think about his own winter needs. He needs some warmer clothes. And he needs to figure out a way to heat his tree-home. Sam builds a fireplace out of clay and pushes holes through the tree bark to allow for ample ventilation. He's preparing as best as he can for the snow and winter to come.