Squirrels belong to the Sciuridae family, a group of rodents that includes tree squirrels, ground squirrels, and flying squirrels. These animals are highly opportunistic feeders, meaning their precise diet varies significantly based on the local habitat and the immediate availability of food sources. While they are often associated with a simple diet of nuts, their menu is quite varied. This flexible foraging strategy keeps them well-nourished throughout the year and provides the necessary energy to support their active, high-metabolism lifestyle.
The Natural Omnivore Diet
Squirrels are classified as omnivores, consuming both plant and animal matter to meet their nutritional needs. The most recognized components of their diet are high-calorie plant items known as hard mast, which includes acorns, hickory nuts, walnuts, and pecans. The high concentration of fats and energy in hard mast fuels their daily activities and allows them to build up fat reserves for survival.
Beyond nuts, squirrels consume a variety of smaller plant-based foods such as seeds, tree buds, flowers, and berries. They also engage in mycophagy, eating fungi like boletes and subterranean truffles, which provide minerals such as potassium and calcium that may be scarce elsewhere. Fungi are often dried on tree branches before consumption, a behavior suggesting a preference for less moisture-heavy food.
The omnivorous nature of the squirrel’s diet is confirmed by their occasional consumption of protein-rich animal matter. While not their primary food source, they opportunistically consume insects, such as grasshoppers and caterpillars, for a protein boost. They have also been documented raiding bird nests for eggs or nestlings, and consuming small vertebrates or carrion when other food sources are scarce. This consumption is especially noticeable in the spring, helping females recover from winter and prepare for breeding.
Seasonal Menu Changes
The squirrel’s diet shifts based on the seasonal availability of resources. During the spring and summer months, the menu is dominated by fresh, easily accessible plant growth. This includes new tree buds, flowers, tender green leaves, and the protein provided by insects, which are abundant during the warmer periods.
As late summer transitions into fall, the focus of their foraging changes entirely to high-fat, storable foods. This is when the hard mast—acorns, walnuts, and hickory nuts—ripen, triggering a period of intense gathering and caching behavior. Squirrels will bury individual nuts across a wide area, a process known as scatter-hoarding, which is important for their winter survival.
When winter arrives, the squirrels rely almost entirely on these buried caches of nuts and seeds, locating them using a combination of memory and their strong sense of smell. During periods of deep snow or extreme cold, when retrieving cached food is difficult, they must turn to less palatable resources. These winter scarcity foods include the inner bark layer (cambium) of certain trees, as well as conifer buds, which provide a minimal but survivable energy source until spring returns.
Foods to Avoid Giving Squirrels
While squirrels are highly adaptable, certain common human foods are inappropriate or toxic to them, offering no nutritional benefit. Processed snacks containing high levels of salt, such as chips or salted nuts, can lead to severe dehydration and kidney stress. Their metabolism is ill-equipped to process the excessive sodium found in these items.
Foods high in refined sugar, like candy or baked goods, are equally problematic, providing empty calories that can lead to malnourishment and health issues. Chocolate is a specific danger because it contains theobromine, a stimulant that small mammals cannot metabolize effectively, making it poisonous even in small amounts.
Moldy foods, including spoiled bread or corn, should also be avoided because they may contain harmful mycotoxins, such as aflatoxins, which can cause severe liver damage. Even seemingly natural items are not ideal; raw peanuts and large quantities of dried corn offer poor nutritional density compared to wild nuts. When providing food to a wild squirrel, it is safest to stick to natural, raw, and unsalted food groups, such as raw walnuts or pecans, to prevent illness or nutritional imbalance.