Squirrels are familiar sights in parks and woodlands, instantly recognizable by their quick movements and bushy tails. They are often observed handling nuts or foraging for seeds, leading many to believe their diet is strictly plant-based. This focus on plant-based activities, such as burying acorns, contributes to confusion about whether these rodents are herbivores or follow a more varied dietary path.
The Clear Answer: Squirrels are Omnivores
Squirrels are classified as omnivores, meaning they naturally consume both plant and animal matter. The classification requires the routine inclusion of both food types in the natural diet. Their digestive system and foraging behavior are adapted to utilize a broad spectrum of nutritional sources. While their diet leans heavily toward vegetation, the consistent intake of animal protein justifies their omnivorous category. This flexibility ensures survival across different seasons and habitats.
The Core Diet: Plant Matter and Fungi
The bulk of a squirrel’s caloric intake comes from plant matter, which provides carbohydrates and fats for their high-energy lifestyle. Their diet concentrates on mast, specifically energy-dense seeds and nuts produced by trees, such as walnuts, hickory nuts, and acorns. These items are consumed in the autumn to build fat reserves for winter, and they rely on cached supplies throughout colder months. In the spring, the diet shifts to include tender tree buds, flowers, and tree sap, a sugary resource accessed by gnawing on bark. Squirrels also consume various fungi, including truffles and mushrooms, often caching them in trees to dry before consumption.
The Evidence of Omnivory
Despite the prevalence of plant-based foods, the inclusion of animal matter establishes the squirrel as an omnivore. Animal protein is consumed year-round, becoming particularly important when high-calorie plant foods are scarce, such as early spring. Squirrels routinely prey upon insects and their larvae, including caterpillars and beetles, which provide a concentrated source of protein and fat. They are opportunistic predators of small vertebrates and their young, with documented instances of consuming bird eggs, nestlings, and even smaller rodents like mice. This protein-rich animal component, though making up a smaller percentage of the total diet, is nutritionally significant for growth and reproduction.
Ecological Role
The varied diet of squirrels gives them a dual role within their native ecosystems. Their habit of scatter-hoarding, where they bury seeds and nuts across a large area, makes them effective seed dispersers. This behavior is responsible for planting countless forgotten seeds, aiding in the regeneration and spread of various tree species, particularly oaks and hickory. Conversely, their consumption of bird eggs and nestlings positions them as minor predators, subtly affecting the populations of certain bird species. By consuming both plant and animal resources, the squirrel acts as a significant link in the food web, influencing both flora and fauna dynamics.