Flying squirrels do not hibernate. They remain active throughout winter, foraging for food and returning to their nests even in freezing temperatures. Unlike true hibernators such as groundhogs or chipmunks, which shut down for weeks or months at a time, flying squirrels stay alert and mobile all season long. What they do instead is a combination of short-term energy conservation, food storage, and social nesting that keeps them alive through the coldest months.
Torpor vs. Hibernation
The distinction matters. Hibernation involves a dramatic, sustained drop in body temperature, heart rate, and metabolism lasting days to months. An animal in hibernation is essentially offline. Torpor is a much lighter version of the same idea: a brief, shallow dip in metabolic activity that helps conserve energy during a cold snap, then reverses quickly.
Flying squirrels may enter torpor during extreme cold, but the episodes are infrequent and remarkably short. Research published in the Journal of Thermal Biology found that when North American flying squirrels did show reduced metabolic rates, those drops were rarely sustained for longer than one hour. The torpor was described as “infrequent” and “shallow,” nothing close to the deep, prolonged shutdown of a true hibernator. The squirrels’ body temperature dips only slightly before they warm back up and resume normal activity.
There are also differences between species. Northern flying squirrels, which live in colder climates, appear more cold-tolerant and may not enter torpor at all. Southern flying squirrels, found in milder regions, are slightly more likely to use these brief torpor bouts when temperatures drop sharply. Both species forage actively through winter, traveling over and tunneling through snow to find food.
How They Stay Warm Without Hibernating
Flying squirrels rely on a few key strategies to survive winter. The most important is communal nesting. Multiple squirrels crowd into a single tree cavity or nest box, and the combined body heat makes a significant difference. Larger groups increase the temperature inside the nest, and the additional fur from several animals adds insulation. The huddled mass also reduces each individual’s exposed surface area, cutting heat loss. In southern flying squirrels, increasing group size offers measurable energy savings. Research on similar small animals has shown that social thermoregulation combined with insulated nests can reduce energy costs by over 50% compared to an isolated animal without shelter.
Flying squirrels also grow a denser winter coat. Their fur thickens seasonally, providing better insulation during cold months. This pelage change, combined with the insulating properties of a well-chosen tree cavity, means the squirrels can maintain their body temperature without the extreme metabolic shutdown that hibernation requires.
Winter Foraging and Food Caching
Staying active all winter means flying squirrels need a reliable food supply. They prepare by caching nuts and seeds in the fall, hiding them in hollow trees, between logs, and in other sheltered spots. Nuts are a primary winter food source, harvested from trees during the fruiting season and stored in various locations.
Some species have developed remarkably creative storage methods. In tropical forests where humidity would cause cached nuts to rot, two species of flying squirrel were filmed using a technique researchers compared to a mortise-and-tenon joint: they wedge nuts between understory twigs, suspending them off the ground where air circulation prevents mold and decomposition. The nuts they store come from trees that fruit between October and December, just before the coldest month, and the stored supply gradually decreases from January through May as the squirrels eat through their reserves.
Northern flying squirrels spend more time on the ground than their southern relatives during winter, actively searching for food beneath the snow. Both species will tunnel through snow to reach cached supplies or find fresh food sources like fungi, lichens, seeds, and tree bark.
Why This Confusion Exists
It’s easy to assume flying squirrels hibernate because they share habitat with animals that do, and because you’re unlikely to spot one in winter. Flying squirrels are strictly nocturnal, so their winter activity happens entirely in the dark. They leave their nests after sunset to forage, then return before dawn. If you have flying squirrels in your yard, they could be active every single winter night without you ever seeing them.
The brief torpor episodes also blur the line for people who’ve heard the term. But torpor in flying squirrels is more like a catnap than a coma. An hour-long dip in metabolic rate on a particularly brutal night is a far cry from a woodchuck sleeping for five months straight. Flying squirrels wake up, eat, socialize, and move through their environment year-round. Winter slows them down slightly, but it never shuts them off.