Squirrels in North America, including the Eastern Gray, Fox, and Red species, are highly efficient, year-round foragers. They exhibit an omnivorous diet that changes drastically with the seasons. Their survival depends on being opportunistic, constantly adapting their food intake based on what is locally available. This adaptable behavior ensures they maintain the high energy levels necessary for daily activity and for surviving the cold winter months.
Preferred Nuts and Seeds
The popular image of a squirrel with a nut is accurate, as they prioritize high-fat, high-energy foods for long-term storage, a process known as caching. They seek items that offer maximum caloric value to sustain them when resources are scarce during winter. Specific favorites include walnuts, hickory nuts, pecans, and hazelnuts, which provide dense packages of fat and protein. Acorns, technically seeds, are a staple part of the diet, especially for Gray and Fox squirrels in oak-heavy environments.
The hard shells of these mast items protect the food from spoilage while buried. Gnawing on the shells also helps keep their continuously growing incisors worn down. Squirrels are strategic in their caching, often burying shelled nuts and relying on spatial memory to relocate hidden stashes. Pine seeds are also collected, often by harvesting and dismantling cones, and are the primary food source for smaller species like the Red squirrel.
Beyond Nuts: Seasonal Food Sources
While nuts provide fat and calories for winter, squirrels supplement their diet with non-nut items to meet hydration and mineral requirements throughout the year. In the spring and summer, when tree nuts are not yet ripe, they consume tender new growth, such as tree buds, bark, and flowers, along with seasonal fruits like mulberries and blackberries. This plant material supplies essential vitamins and water that are less concentrated in dried, stored foods.
As omnivores, squirrels incorporate animal matter into their diet, particularly when seeking protein. They forage for insects, including grasshoppers and caterpillars, and occasionally consume bird eggs or nestlings. Fungi, such as mushrooms and truffles, are also sought out because they are rich in nitrogen and minerals like calcium and potassium. Squirrels may carry a mushroom and hang it up on a branch to dry before storing it for later use.
Foods to Strictly Avoid
If feeding squirrels, the public must understand that many common human foods are detrimental or toxic to these small animals. Processed foods, including bread, crackers, candy, and breakfast cereals, should be avoided. These items offer empty calories and can lead to digestive issues or malnutrition due to their high sugar and carbohydrate content.
Salted nuts and salty snacks are dangerous because high sodium content can overwork a squirrel’s kidneys, leading to severe dehydration and toxicity. Excessive corn consumption can interfere with calcium absorption, potentially leading to bone deficiencies. Raw peanuts are problematic because they are legumes, not true nuts, and can harbor aflatoxin, a toxic mold. Specific toxins to avoid include theobromine found in chocolate, and persin, a fungicidal toxin present in the skin and pits of avocados.