Flying squirrels, native to North American forests, are distinctive for their nocturnal activity and unique mode of movement. These small mammals do not actually fly but glide through the air using the patagium, a specialized fold of skin stretching between their wrists and ankles. This ability allows them to travel efficiently between trees in their arboreal habitat while searching for food at night. The diet of both the Southern (Glaucomys volans) and Northern (Glaucomys sabrinus) flying squirrels is diverse, classifying them as omnivores whose meals change significantly depending on the season and local environment.
The Core Diet: Plant and Fungal Matter
The bulk of a flying squirrel’s diet comes from various plant-based sources, particularly the seeds and nuts of hardwood trees. They consume large, high-calorie nuts like hickory nuts, beechnuts, and acorns, especially when preparing for colder months. They also eat smaller seeds, tree buds, tree sap, and the inner bark of trees such as the sugar maple, particularly during the spring when other sources are scarce.
Fungi, including mushrooms and underground truffles, are another cornerstone of their diet and an important source of water and vitamin D. For the Northern flying squirrel, fungi and lichens often make up the majority of their diet, sometimes accounting for as much as 85% of total food intake. They actively seek out truffles, the fruiting bodies of mycorrhizal fungi, by sniffing and digging them up from the forest floor. This consumption is an important ecological function, as the squirrels disperse fungal spores in their droppings, which helps inoculate tree roots and promotes forest health.
The Role of Protein: Insects and Small Prey
While plant matter is foundational, flying squirrels actively supplement their diet with animal protein necessary for growth and tissue repair. They are considered one of the most carnivorous species of tree squirrel; the Southern flying squirrel consumes a greater proportion of animal matter than its Northern counterpart. This protein is often sourced from insects, including moths, beetles, and various larvae, which are readily available during warmer months.
They opportunistically consume small vertebrate prey, particularly when energy demands are high, such as for breeding females. This includes raiding bird nests for eggs and nestlings, or occasionally preying on small rodents like mice and shrews. Flying squirrels will also feed on carrion, demonstrating their adaptable nature as scavengers in the forest ecosystem.
Dietary Adaptations and Seasonal Changes
The diet of flying squirrels shifts dramatically throughout the year based on resource availability. During the summer and fall, they gorge themselves on seasonal bounty, including fresh fruits, berries, and insects, while simultaneously caching nuts and seeds. These cached items are stored in locations like tree cavities, underground, or in their nests, to be retrieved during the scarce winter months.
Flying squirrels do not hibernate, relying heavily on stored food and less-palatable winter staples to survive the cold. The winter diet often consists of cached nuts, conifer seeds, and lichens, particularly Bryoria species for the Northern flying squirrel in snow-heavy regions. They are also opportunistic feeders at bird feeders in human environments, drawn to high-fat foods like suet and sunflower seeds. Their ability to glide allows them to access feeders protected from climbing gray squirrels, and their nocturnal schedule means they are often unseen.