Do Mice Hibernate? Why They Move Indoors in Autumn
No, mice do not hibernate: house mice, deer mice and voles all stay active through the winter, and the cold is the reason they move into houses rather than a reason to sleep. House mice keep feeding and can breed year round wherever food and shelter are stable. Deer mice may drop into torpor for a few hours on a severe night, which is not hibernation. The US mice best known for true hibernation, the jumping mice, live in wetland and streamside vegetation and are not household pests.
That is why mouse problems tend to start between September and November and do not end on their own in spring. Below: which small mammals hibernate, what mice do instead, and what our iNaturalist analysis shows across the year.
Which small mammals hibernate, and which only slow down
| Animal | Hibernates? | What it does in winter | Gets into houses? |
|---|---|---|---|
| House mouse | No | Stays active; breeds year round where food and shelter are stable | Yes, mainly in autumn |
| Deer mouse and white-footed mouse (“field mice”) | No | Nests in family groups; may become torpid for hours in severe weather | Often in cabins, empty homes and other structures |
| Meadow vole | No | Active day and night year round; tunnels through snow | Usually not; UC IPM notes voles are poor climbers |
| Meadow jumping mouse | Yes | True hibernation of roughly six and a half to eight months | Not a household pest |
| Norway rat | No | Stays active; breeding peaks in spring and autumn | Yes |
| Big brown bat | Yes | Hibernates singly; one to four sometimes overwinter in a house | Sometimes |
The rodents that live alongside people do not hibernate. If you hear scratching in a wall in January, a hibernating animal is the least likely explanation; our guide to mice in walls covers how to tell the sounds apart.
Why mice do not hibernate
Hibernation is a deep drop in body temperature and metabolism that an animal holds for days or weeks at a time, over a season that can last months. A hibernating ground squirrel runs at a body temperature of about 5 °C (41 °F) with a heart rate near 10 beats a minute. House mice do something different: they stay warm and keep eating.
A review of cold adaptation in wild house mice by Barnett and Dickson found that the house mouse “can thrive in natural environments much below its optimum temperature.” In severe cold, around 0 °C (32 °F), wild-type mice first shiver and cut their activity, then switch to raised heat production without shivering and build better nests. Over generations in the cold, laboratory lines of wild mice became heavier and fatter and matured earlier. That is the opposite strategy to hibernation: burn more fuel, insulate better, and keep going.
Cold still has costs. The same review notes that in free-living populations cold lowers fertility and may prevent breeding, and that in severe cold nestling deaths rise. A heated house removes those costs, which is why a mouse that gets indoors in October can breed through the winter.
Torpor: the short version mice can use
Mice do have an emergency setting called daily torpor, a drop in body temperature that lasts hours rather than weeks. In a study of laboratory house mice by Swoap and Gutilla, mice kept at 19 °C (about 66 °F) and denied food overnight all entered torpor. Core body temperature fell from 36.6 °C (about 98 °F) to an average minimum of 25.9 °C (about 79 °F), and heart rate fell from 607 to an average minimum of 158 beats a minute. Fed mice in the same room did not do this.
A torpid mouse still runs a heart rate more than ten times that of a hibernating ground squirrel, and it wakes the same day. In laboratory mice it was triggered by fasting, so a mouse in a house with food has little reason to use it.
Deer mice and torpor
Deer mice, the “field mice” of most of North America, use torpor more readily. UC IPM states that deer mice do not hibernate “but they may become dormant (torpid) when the weather is especially severe,” and that they nest in family groups through the winter. Laboratory work by Pivorun and Tannenbaum induced torpor in deer mice by halving their food, and classed bouts lasting more than 300 minutes, with body temperatures of 20 °C (68 °F) or below, as long, deep bouts.
Day length matters too. Geiser and colleagues kept deer mice for more than eight weeks under winter, equinox and summer day lengths. Torpor occurred in 71, 70 and 14 per cent of the mice respectively, and bouts lasted longest under short winter days.
How long do mice hibernate?
They do not hibernate at all, so there is no hibernation period to wait out. The longest a house mouse or deer mouse goes dormant is a torpor bout of hours. If mice seem to vanish over winter, the explanations are more ordinary: they have moved deeper into the structure, they have been caught or poisoned, or they were never there in the numbers you thought. Our guide to how to tell if mice are gone sets out how to check.
Do field mice hibernate?
In the US, “field mouse” usually means a deer mouse or white-footed mouse, and neither hibernates. The exception is the jumping mice, which are true hibernators. Frey’s 2015 study of the New Mexico meadow jumping mouse found an active season of 162 days in a low valley population and about 124 to 135 days in mountain populations, with the last animals entering hibernation in mid to late October. In the eastern US, adults have all gone into hibernation by about the end of the first week of September, according to work Frey cites.
Frey describes the species as a specialist of riparian habitats, foraging at night in herbaceous wetland vegetation. It is not a household pest. If you have mice indoors in winter, you do not have jumping mice.
Where do mice go in winter?
Outdoors, deer mice nest in tree hollows, stumps, under logs and rocks, and in old bird and squirrel nests, often caching seeds near the nest in autumn, according to UC IPM. Voles carry on under the snow; UC IPM notes they are active “day and night, year-round” and burrow in and through the snow, which is why their bark damage often goes unnoticed until the thaw.
House mice that live outdoors take a different route. UC IPM states that where outdoor populations exist, house mice “frequently enter homes in autumn when nighttime temperatures become colder.” They can squeeze under gaps a quarter of an inch tall, and once inside they seldom travel more than about 30 feet from the nest. The usual winter quarters are wall voids, the space under kitchen appliances, cupboards, attics, basements and garages. What draws them to a particular house is covered in our guide to what attracts mice, so we will not repeat it here.
Insects that overwinter in walls behave differently; our guide to bugs in the house in winter covers them.
Do mice like cold, and do they die in the cold?
Mice tolerate cold well but do not prefer it. Swoap and Gutilla describe 19 °C as about 10 °C below the mouse’s thermoneutral zone, the temperature band where it does not need to spend extra energy to keep warm. In other words, a room most people find comfortable is chilly for a mouse.
The wild house mice in Barnett’s work survived and bred in severe cold, at a cost to fertility and nestling survival. UC IPM lists “climate-related challenges” among the main causes of death in wild house mice, alongside disease, predation, human management and starvation. In practice, cold kills mice mostly by making food harder to find and nests harder to keep warm, which is the same pressure that pushes them indoors.
When mice are recorded through the year
The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026, shows the difference between a hibernator and a mouse plainly. The chart below plots raw monthly record counts, each row scaled to its own peak.
Little brown bats, which Purdue notes hibernate in caves, almost vanish from the records in winter: 143 US records in August against 5 in November. House mice show no winter gap at all. Their records climb from 235 in June to 443 in October, and January (245) has more records than June. Norway rats follow a gentler curve, from 397 in January to 760 in September. Deer mice, which live mostly outdoors, peak at 1,015 in May and still log 509 in January.
These are sightings, mostly outdoors, not counts of infested houses. Our separate analysis of rodent complaint data from city 311 lines, which are mostly rat calls, makes a related point: Chicago’s rat complaints run from an index of 147 in July to 56 in December, but they never stop. Rodent activity eases in winter; it does not pause.
What month do mice go away?
No month reliably makes mice leave. Mice that got indoors in autumn tend to stay as long as food and nesting cover last, because UC IPM notes that with plentiful, stable resources house mice “can reproduce year-round, resulting in high population densities that last for months to years.” Outdoors, the wildlife damage handbook notes that house mice breed mostly in spring and autumn, so outdoor numbers swell after each breeding season.
| Season | What house mice usually do | What it means at home |
|---|---|---|
| Spring | Outdoor breeding season; some mice disperse outside | An indoor population with food does not leave on its own |
| Summer | Mostly outdoors; fewest mouse records of the year in June | Best window to seal gaps before autumn |
| Autumn | Second outdoor breeding peak; move indoors as nights cool | First droppings and wall noises usually appear |
| Winter | Active indoors; breeding continues where food is stable | Numbers can grow until you trap and exclude |
The practical answer is that mice go away when they are trapped out and the gaps are sealed, not when the calendar turns. Our guide to signs of mice in the house helps you judge whether you still have them.
Do rats hibernate?
No. Norway rats stay active all year, and the Illinois Department of Public Health rat fact sheet notes that their breeding “is most active in spring and fall,” with an average of four to six litters a year. The iNaturalist records above show Norway rats recorded in every month of the year.
Do mice hibernate in summer, and do they freeze when scared?
Mice have no summer dormancy either; in summer they are simply more likely to be living outdoors.
Freezing when scared is real, but it has nothing to do with hibernation. It is a defensive reflex: researchers measuring mouse responses to predator threats record freezing alongside flight and defensive attack, and the fox odour compound TMT produces “robust freezing” in naive mice and rats. A mouse that goes rigid when the light comes on is using a defence, not shutting down for the season.
What to do this autumn
- Seal before the cold arrives. Close gaps a quarter of an inch or larger; UC IPM advises sealing openings for water pipes, vents and utility cables with metal or concrete, and small cracks with wire screen or coarse steel wool.
- Trap promptly. A winter population can keep breeding.
- Clean up safely. If deer mice have been in a shed, cabin or garage, follow our hantavirus and mouse dropping cleanup guide and never sweep or vacuum droppings.
- Know when to call someone. Signs in several rooms, mice in a deer mouse area, or activity that returns after trapping are reasons to bring in a licensed professional; our guide to when to call pest control for mice sets out the thresholds.
How long the mice you have will live, and how quickly they replace themselves, is covered in how long do mice live.
Frequently asked questions
Do mice hibernate in the winter?
No. House mice, deer mice and voles all stay active through the winter. House mice move into buildings as autumn nights turn cold and can breed year round where food is stable. Deer mice may become torpid for a few hours in severe weather, which is a short daily dormancy, not hibernation. The best-known US mice that truly hibernate are the jumping mice, which live in wetland vegetation and are not household pests.
What is a mouse’s worst enemy?
For wild house mice, the main causes of death that UC IPM lists are disease, predation, human management, climate-related challenges and starvation. Owls, hawks, snakes, foxes and cats all take mice. Indoors, though, predators rarely solve the problem: UC IPM notes that cats and dogs seldom control rodent populations and that their presence can make mice more secretive, giving a false impression that numbers have fallen.
How many mice are in your house if you see one?
There is no reliable multiplier, and published guidance does not give one. A single sighting can be one wanderer or part of a group. Evidence is a better guide: droppings in two or more separate rooms, or regular noise in walls or ceilings, point to an established population. Because a female can have 5 to 10 litters a year, according to UC IPM, acting on the first signs is much easier than waiting.
Why do mice suddenly disappear?
Not because they have gone into hibernation. The usual reasons are that they have been caught or poisoned, that they have moved to another part of the building, or that a cat or other predator has made them more cautious; UC IPM notes predators can make rodents more cryptic without reducing their numbers. Flour patches and unset baited traps left for a week show whether any are still active.
Do mice like cold?
They tolerate it but do not prefer it. A room at 19 °C (about 66 °F) is roughly 10 °C below the mouse’s thermoneutral zone, so a house mouse spends extra energy staying warm at temperatures people find comfortable. Wild house mice can survive and breed in severe cold by raising their heat production and building better nests, but cold lowers their fertility, which is why heated buildings suit them so well.
Sources
- University of California Statewide IPM Program, Pest Notes: House Mouse, Publication 7483 (Quinn, 2025).
- University of California Statewide IPM Program, Pest Notes: Deer Mouse, Publication 74161.
- University of California Statewide IPM Program, Pest Notes: Voles (Meadow Mice), Publication 7439.
- Timm, R. M., House Mice, in Prevention and Control of Wildlife Damage, University of Nebraska Cooperative Extension, 1994.
- Barnett, S. A. and Dickson, R. G., Wild mice in the cold: some findings on adaptation, Biological Reviews 64(4), 1989.
- Swoap, S. J. and Gutilla, M. J., Cardiovascular changes during daily torpor in the laboratory mouse, American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 2009.
- Geiser, F., McAllan, B. M., Kenagy, G. J. and Hiebert, S. M., Photoperiod affects daily torpor and tissue fatty acid composition in deer mice, Naturwissenschaften, 2007.
- Pivorun, E. B. and Tannenbaum, M. G., Naloxone inhibition of stress-induced daily torpor, Life Sciences 34(22), 1984.
- Frey, J. K., Variation in phenology of hibernation and reproduction in the endangered New Mexico meadow jumping mouse, PeerJ, 2015.
- Purdue University Extension, Bats, ADM-11.
- Illinois Department of Public Health, Rat Fact Sheet.
- Blanchard, D. C., Griebel, G. and Blanchard, R. J., The Mouse Defense Test Battery, European Journal of Pharmacology, 2003; Rosen, J. B., Asok, A. and Chakraborty, T., The smell of fear, Frontiers in Neuroscience, 2015.
- The Pest Control Brief analysis of iNaturalist research-grade records, pulled October 2026; The Pest Control Brief analysis of Chicago and New York 311 rodent complaints.
