The days are getting shorter and the temperature is dropping. the squirrel responds to these cues by

The squirrel will go searching for food to collect food such as nuts, and or acorns. During the fall the squirrel caches nuts over a wide area using a technique called “scatter hoarding” in which the squirrel bites and licks each nut before the squirrel buries it. Through out the winter the squirrel will retrieve the nuts. Using it’s memory and it’s sense of smell.

Searching for food, and protecting its food for the hibernation that is soon to occur. They stay hidden till about spring.

The answer is ozone layer.