Chipmunks, small, striped rodents often seen darting across yards, are a familiar sight during warmer months. As autumn progresses and days shorten, these creatures disappear from view, prompting many to wonder about their whereabouts during winter.
Chipmunks and Winter Dormancy
Chipmunks do not enter true hibernation like some larger mammals. Instead, they undergo a winter survival strategy called torpor, often described as “semi-hibernation.” This state allows them to conserve energy when food is scarce and temperatures drop. Unlike true hibernators, chipmunks periodically awaken from torpor, remaining somewhat active within their burrows.
Getting Ready for Winter
As the chill of autumn sets in, chipmunks embark on a diligent preparation phase for the coming winter. Their primary focus during this time is gathering and storing a substantial food supply within their elaborate underground burrows. Chipmunks are known for their impressive food-caching habits, using their expandable cheek pouches to transport nuts, seeds, berries, and other provisions back to their subterranean larders. Some chipmunks have been found to hoard up to 8 pounds of food, which is a considerable amount for an animal weighing only a few ounces.
In addition to food storage, chipmunks meticulously construct and modify their burrow systems, which can extend up to 30 feet long and be several feet deep. These intricate homes feature multiple chambers for nesting, food storage, and even separate areas for waste. The burrows provide a secure and insulated environment, helping to protect the chipmunks from freezing temperatures and predators throughout the winter months. Some entrances may be camouflaged or plugged to deter unwanted guests, ensuring a safe retreat underground.
Inside the Winter Burrow
Once inside their winter burrows, chipmunks enter the state of torpor, where their physiological functions undergo a notable slowdown. During this period, their body temperature can drop significantly from a normal range of 96-106 degrees Fahrenheit to as low as 40 degrees Fahrenheit, closely matching the burrow’s ambient temperature. Their heart rate dramatically slows from an active rate of around 350 beats per minute to as few as 4-15 beats per minute, and breathing can decrease from 60 breaths per minute to fewer than 20. This reduction in metabolic activity conserves energy, but these changes are less extreme and continuous than in true hibernators.
Chipmunks typically wake every few days from their torpid state, a process that can take a couple of hours as their body temperature rises. During these arousal periods, they access their cached food supply to replenish energy stores and may also excrete waste. As warmer temperatures arrive in spring, chipmunks emerge from their burrows, resuming their active foraging and daily routines.