Squirrels are a familiar presence in North American landscapes, and their activity is governed by the rhythm of the seasons. These tree squirrels are diurnal, meaning their lives revolve around the daylight hours. The intensity and focus of their activity fluctuate throughout the year. The transition from one season to the next triggers distinct shifts in behavior, driven primarily by the demands of reproduction, food availability, and the need to prepare for periods of scarcity. Seasonal changes in daylight length and temperature dictate their daily schedule, with their visible energy peaking during the spring and autumn months.
Spring: Peak Energy and Breeding
Spring marks the first major surge in squirrel activity, driven by the end of winter’s relative inactivity and the onset of the breeding season. Males become noticeably more visible as they aggressively compete for access to females. This competition manifests as frenetic, noisy “mating chases,” where multiple males pursue a single female, requiring immense, sudden energy output.
The high energy output continues as females focus on gestation and constructing or renovating their nests, known as dreys, to house the first litter of the year. Dreys are typically built high in tree branches from sticks, with a soft, insulated lining of moss and leaves. Squirrels also intensify foraging to rebuild body reserves depleted during the colder months, seeking out newly sprouted buds, flowers, and any remaining caches from the previous autumn.
Summer: Sustained Foraging and Growth
Summer activity shifts from frantic courtship to sustained, intensive foraging focused on supporting the growing litters. Females, who may have a second litter, must continuously accumulate proteins and carbohydrates to sustain themselves and their young, which begin to venture out of the drey around seven weeks old. Juvenile squirrels, born in the spring, also contribute to the high level of daytime activity as they learn essential survival and foraging skills.
Squirrel activity often exhibits a bimodal pattern, with distinct peaks in the early morning and late afternoon. This schedule allows them to avoid the most intense heat of the midday sun, conserving energy while maximizing the use of longer daylight hours for finding food. Their diet diversifies to include fruits, berries, and mushrooms, providing nutrients for growth and setting the stage for fat accumulation that begins in the late summer.
Autumn: Preparation for Winter
Autumn represents the second peak in a squirrel’s annual activity cycle, driven by the need for winter preparation. This period is characterized by an intense focus on consuming high-fat foods, such as acorns, walnuts, and hickory nuts, to build up body fat reserves for winter survival. The sheer volume of this feeding often makes squirrels look noticeably plumper by the time the first frosts arrive.
The most recognizable autumn behavior is caching, or scatter hoarding, where squirrels bury thousands of individual food items across their territory. This highly visible activity ensures a dispersed winter food supply, which they locate later using a combination of memory and their developed sense of smell. Squirrels spend a significant portion of their autumn time searching, caching, and eating, making them appear exceptionally busy.
Winter: Survival and Reduced Visibility
Winter marks the period of lowest visibility for tree squirrels, although they do not hibernate like ground squirrels. Instead, they enter periods of torpor, a state where their metabolism slows down to conserve energy. They rely heavily on the insulated nests they have fortified and the caches they buried during the autumn months.
Squirrels only emerge from their dreys to forage on warmer, sunny days. Their activity pattern becomes unimodal, typically peaking around midday when temperatures are highest. This strategic inactivity minimizes the energy costs associated with maintaining body temperature. While they remain physiologically active, their observable presence in the environment is significantly reduced until spring.