The common image of a squirrel is that of a frantic forager burying acorns and snatching nuts, leading to the widespread belief that these animals are strict vegetarians. Squirrels belong to the family Sciuridae, which includes over 200 species like tree squirrels, ground squirrels, and flying squirrels. While their diet is heavily dominated by plant matter, the reality is that a squirrel’s nutritional strategy is far more flexible than a simple herbivorous label suggests. The question of whether squirrels are truly carnivorous can only be answered by exploring their entire opportunistic diet.
The Standard Diet: Herbivore by Necessity
Squirrels primarily subsist on a diet of plant-based foods, which forms the vast majority of their caloric and nutrient intake. This baseline diet consists of seeds, nuts, fruits, and fungi readily available in their diverse habitats. They rely heavily on high-energy sources like acorns, hickory nuts, and pine nuts, which they store to survive through periods of scarcity, especially winter.
Their physical characteristics are well-suited for processing these tough plant materials. Squirrels possess four sharp, chisel-like incisors that grow continuously, allowing them to gnaw through hard shells and woody exteriors. Beyond the familiar nuts, their foraging includes tree buds, flowers, bark, and even the cambium layer of wood. The consumption of fungi, such as mushrooms and truffles, provides them with nitrogen and essential minerals like calcium and potassium, which are often scarce in seeds.
The Reality of Omnivory: When Squirrels Consume Animal Matter
Despite their plant-focused preferences, squirrels are opportunistic omnivores. This behavior is a key adaptation that allows them to thrive in various environments by capitalizing on whatever food is available. The consumption of animal matter typically accounts for a smaller percentage of their overall diet, often ranging from 20 to 30 percent, but it is a consistent part of their foraging.
Specific animal-based items are regularly included in their menu. Insects and their larvae, such as beetles, grubs, and caterpillars, are common targets and provide a quick source of protein. Their occasional predation on other vertebrates includes raiding bird nests for eggs and vulnerable nestlings. Some species will also consume small mammals, like mice, frogs, or lizards, when the chance arises.
The consumption of animal matter extends to scavenging, with squirrels occasionally feeding on carrion. Certain species, like the Southern flying squirrel, rely more heavily on insects. This flexible approach demonstrates that while they are not true carnivores, they readily consume meat to supplement their primary diet.
Nutritional Drivers for Protein Consumption
The underlying reason for a squirrel’s omnivorous behavior is directly tied to meeting specific physiological demands. Plant-based foods often lack the complete protein and certain micronutrients that are necessary for peak health. Squirrels cannot digest cellulose, so they must seek out foods that are rich in protein, fats, and carbohydrates.
Protein consumption becomes particularly important during periods of high biological stress, such as the breeding season. Pregnant and lactating female squirrels require significantly higher levels of protein and calcium for gestation and milk production, which drives them to seek out animal sources like eggs and insects. Similarly, juvenile squirrels undergoing rapid growth need a protein-rich diet to support bone and muscle development.
Environmental factors also contribute to this dietary shift, as squirrels will consume animal matter when their preferred high-energy plant foods are scarce. Early spring, for instance, is a difficult time because buried nuts begin to sprout. During these lean periods, protein-rich insects and small animals act as a stand-in to prevent nutritional deficiencies and compensate for low-quality plant foods.