QuestionEastern chipmunk
Do Chipmunks Hibernate? Winter Torpor and Food Stores
Eastern chipmunks do not hibernate in the deep, nonstop way groundhogs do, but they do spend most of the winter underground in a state called torpor. For several days at a time their body temperature and heart rate drop sharply. Then they wake, eat from the seeds and nuts stored in their burrow, and go back into torpor.
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What chipmunks do in winter
The eastern chipmunk spends the cold months in its burrow, usually from late October or November until March or April in the northern and central parts of its range. During that time it is rarely seen, which is why many people assume it hibernates like a bear or groundhog.
Inside the burrow, the chipmunk curls up in a nest of dry leaves in a chamber below the frost line. Its winter follows a repeating cycle:
- It enters torpor and its body cools to near the temperature of the burrow.
- It stays torpid for a few days, often up to about a week.
- It warms up again, wakes, eats from its larder and uses a separate toilet area.
- It returns to torpor.
On mild, sunny days in midwinter some chipmunks briefly come above ground. In the south of the range, where winters are short and mild, chipmunks may be active on many winter days.
Hibernation vs torpor: what is the difference?
Biologists use torpor for any controlled drop in body temperature and metabolism that saves energy. Hibernation is long, repeated torpor through a whole season. In that sense, eastern chipmunks are hibernators. But they differ from “fat-storing” hibernators in an important way.
| Feature | Eastern chipmunk | Groundhog |
|---|---|---|
| Winter fuel | Food stored in the burrow | Body fat built up in summer and fall |
| Fat reserves before winter | Small | Large; can lose a third or more of body weight |
| Eats during winter | Yes, between torpor bouts | No |
| Typical torpor bout | A few days, often up to about a week | Often a week or longer |
| Winter body temperature | Drops close to burrow temperature during torpor | A few degrees above freezing during torpor |
A groundhog is a classic fat-storing hibernator: it eats heavily all summer and then lives on its fat. The chipmunk is a food-storing hibernator: its larder of seeds and nuts is its winter fuel. Neither strategy is better; each fits the animal’s body size and diet.
How chipmunk torpor works
During torpor, a chipmunk’s body temperature falls from about 37 °C (99 °F) to just a few degrees above the temperature of its burrow, which in winter is often only a few degrees above freezing. Its heart rate and breathing slow to a small fraction of normal, and its energy use drops dramatically.
Waking up is costly. To rewarm, the chipmunk shivers and burns energy to heat its body back to normal, a process that takes a few hours. That is why a good food store is essential: each time it wakes, it needs to refuel.
Research on wild eastern chipmunks has shown that the amount of food matters. Chipmunks with large food stores spend less time in deep torpor and more time at normal body temperature, while animals with small stores rely on torpor more heavily. This flexibility helps them cope with good and bad nut years.
Why food stores matter so much
In autumn, eastern chipmunks spend much of the day carrying acorns, beechnuts, hickory nuts and seeds back to their burrows in their cheek pouches. A larder may contain hundreds or even thousands of items. Read more in what chipmunks eat.
The size of the autumn seed and nut crop strongly affects survival. After a heavy acorn or beechnut year, many chipmunks survive winter and often breed early the following spring. After a poor year, winter losses are higher.
When do chipmunks come out in spring?
Most chipmunks reappear in March or April. Males often emerge first, sometimes when patches of snow remain, and begin roaming in search of females. The first breeding season of the year runs from about February to April, and the first litters are born in spring.
Early spring is a lean time. Winter stores may be running low and new seeds are scarce, so chipmunks feed on any remaining stores, buds, early tree seeds such as red maple, and insects.
How do other small mammals handle winter?
Different small mammals solve the problem of winter in different ways:
- Groundhogs hibernate deeply on stored fat.
- Eastern chipmunks use torpor and a burrow full of food.
- Tree squirrels, such as the eastern gray squirrel, do not hibernate at all; they stay active and dig up buried nuts. See do squirrels hibernate?
- Many bats and hedgehogs hibernate on body fat, waking only occasionally.
For more examples, see the list of animals that hibernate.
Myths and facts about chipmunks in winter
Myth: chipmunks sleep straight through the winter. They wake every few days to eat and move around the burrow.
Myth: a chipmunk seen in January must be sick. On a mild, sunny winter day, a healthy chipmunk may simply be taking a short break from torpor above ground.
Fact: chipmunks keep a tidy winter home. Food, nest and waste are usually kept in separate parts of the burrow, which helps keep the nest clean over many months underground.
Frequently asked questions
When do chipmunks go into hibernation?
In much of the northeastern United States and southern Canada, eastern chipmunks retreat to their burrows for the winter in late October or November. The exact timing depends on the weather, the food supply and the individual animal.
When do chipmunks come out in spring?
Most eastern chipmunks reappear in March or April. Males often emerge first, sometimes while there is still snow on the ground, to look for females at the start of the breeding season.
Do chipmunks wake up in winter?
Yes. Chipmunks rouse from torpor every few days to eat from their food store and to use a separate toilet chamber in the burrow. On mild, sunny winter days, some even come above ground for a short time.
Do chipmunks get fat before winter?
Not much. Unlike groundhogs, eastern chipmunks do not build up large fat reserves. They survive winter mainly on the seeds and nuts they hoarded in their burrow in late summer and autumn.
Do western chipmunks hibernate too?
Most chipmunk species in cold climates use winter torpor in a similar way, waking to feed on stored food. In milder areas, some western chipmunks stay active for much of the winter.
Sources and further reading
- Animal Diversity Web (University of Michigan), "Tamias striatus"
- Snyder, D. P., "Tamias striatus", Mammalian Species 168 (1982)
- Mass Audubon, "Chipmunks"
Cite this page
“Do Chipmunks Hibernate? Winter Torpor and Food Stores.” Animal Atlas, https://animals.bigworldlist.com/questions/do-chipmunks-hibernate/.
