Chipmunks, small striped members of the squirrel family, largely disappear once cold weather arrives, leading many to wonder where they go. These highly active rodents do not migrate but instead use a specialized survival strategy to endure the long, resource-scarce winter months. Their solution involves retreating to a meticulously constructed underground home where they enter a state of reduced metabolic activity. This period of dormancy allows them to conserve energy until the warmth of spring returns.
Pre-Winter Preparations
Starting in the late summer and continuing through autumn, chipmunks enter a period of intense activity focused on gathering necessary supplies for their winter retreat. Their primary preparation involves collecting and transporting large quantities of non-perishable food, such as nuts, seeds, and berries, into their subterranean dwelling. Chipmunks utilize expandable cheek pouches to maximize carrying capacity, sometimes stuffing them with thousands of small seeds before going underground.
The chipmunk’s winter survival strategy relies heavily on these stored provisions rather than accumulating large amounts of body fat. Unlike some larger hibernators, chipmunks stockpile a larder of food within their burrow to sustain them through periodic wake-ups. This cache can be substantial, with single burrows sometimes containing tens of thousands of seeds.
Construction of the Winter Burrow
The winter burrow serves as a highly insulated, multi-chambered fortress that protects the chipmunk from freezing temperatures and predators. These subterranean homes are excavated up to three feet deep, often extending well below the frost line where soil temperatures remain relatively stable. The tunnels can reach a total length of up to 30 feet in older, more complex systems.
The core of the structure is the nesting chamber, which is lined with soft insulating materials like dried leaves and grass to create a cozy resting place. Adjacent to this chamber is the food cache, or larder, where the autumn harvest is stored for easy access during the dormant period. Chipmunks also incorporate drainage tunnels that extend downward to collect water, helping to keep the main living area dry.
To maintain internal temperature stability and deter unwanted visitors, the chipmunk typically plugs the main entrance with soil and debris once it retreats for the season. While the burrow system may have several entrances, these are often camouflaged under rocks, logs, or shrubbery. This construction ensures a secure, warm environment for the months ahead.
The Winter State of Torpor
Once sealed inside their burrow, chipmunks enter an energy-saving state known as torpor, which differs from true hibernation. They are considered facultative hibernators, meaning they enter long bouts of dormancy but wake up at regular intervals. They generally arouse every few days or weeks to move around, eat from their stored food supply, and void waste.
During the torpor phase, physiological functions undergo dramatic suppression to conserve energy. Body temperature can drop significantly, often falling to the mid-40s Fahrenheit, close to the ambient burrow temperature. This cooling is accompanied by a severe reduction in heart rate, slowing from approximately 350 beats per minute to fewer than 10 beats per minute.
These periodic waking events are energetically expensive, requiring the animal to rapidly raise its body temperature to normal levels. The stored food cache is important during these brief active periods, replenishing the energy used during arousal. The chipmunk consumes provisions before allowing its metabolism to slow down and re-entering torpor.