A well-known fact (or at least it should be well-known) is that squirrels don't hibernate as much during the winter anymore. Modern society demands full attention throughout the year. But despite adjusting to the winter hours of normal day-night cycles, squirrels still have a marked decrease in metabolism and energy during the winter months. Such things lead to weight gain, long naps, and over-large diets to pack on winter fat for the cold months. Some report an increased disappearance rate during these months of people who happen to know squirrels, but that's just totally conjecture.
Another picture in the " samael sketched and I lined/flat colored" series.