North American tree squirrels, such as the Eastern Gray Squirrel (Sciurus carolinensis) and the Fox Squirrel (Sciurus niger), are prominent features of many landscapes. These small mammals are strictly diurnal, meaning their entire cycle of activity, including foraging and socializing, occurs exclusively during daylight hours. Their daily rhythm is governed primarily by the sun.
Understanding the Diurnal Schedule
Squirrel activity throughout the spring, summer, and fall generally follows a bimodal pattern, characterized by two bursts of high energy separated by a period of rest. The first and more intense peak begins shortly after sunrise. Many species become active immediately prior to dawn or within 30 minutes of the sun appearing above the horizon. This morning rush is designed to maximize energy intake early in the day.
The intensity then subsides, leading to a noticeable mid-day lull that can last for several hours, especially during hot summer days. Activity resumes for a second, less sustained peak in the late afternoon, typically two to three hours before dusk. This bimodal schedule is the standard for most of the year, ensuring final foraging is completed before the animals retreat to their nests.
Key Environmental Influences on Activity
The timing of a squirrel’s emergence and retreat is influenced by seasonal changes in photoperiod, or the duration of daylight hours. During summer months, squirrels may leave their nest, or drey, up to three hours earlier than they would in the winter. Total active time can increase from approximately four hours a day in winter to over 11 hours in the late summer, reflecting greater resource availability.
Temperature also modifies the daily schedule, often dictating the timing of the mid-day rest period. On very hot days, the mid-day lull becomes more pronounced, with squirrels retreating to their nests or adopting a heat-dispersing posture on branches. In colder winter months, the bimodal pattern often disappears, consolidating into a single, less intense activity period centered around midday. Heavy precipitation or strong winds can also cause temporary retreats back to the shelter of the nest.
The Full Daily Cycle
The two daily peaks of activity serve different purposes. The early morning peak focuses on intensive foraging and scatter-hoarding, which involves burying individual food items across many locations. During the fall, over 60% of a squirrel’s active time may be spent searching, caching, or eating food to prepare for the lean winter months.
Following the mid-day rest, the late afternoon activity is devoted to social interactions, territorial maintenance, and the final gathering of perishable food items. As sunset approaches, activity rapidly decreases, and squirrels retire to their insulated nests or dreys, which are often built high in tree branches. They remain inside their nests until the following morning’s light triggers their emergence.