Squirrels are a fixture in many yards and parks, constantly foraging and building their nests, but their diet occasionally includes an unusual item: tree bark. The short answer to whether squirrels eat bark is yes, they do, but the behavior is less about consuming the rough outer layer and more about accessing the nutrient-dense tissues beneath it. This practice is not random and usually signals a specific need the squirrel is trying to fulfill, often when their preferred food sources are unavailable.
The Direct Answer: Why Squirrels Consume Bark
Squirrels are not typically interested in the tough, protective outer bark, but instead target the softer, living tissues found immediately underneath, specifically the phloem and cambium layers. The cambium is a thin, growing layer that produces the cells for both the inner wood and the outer bark, and it is rich in sugars and starches. This high concentration of carbohydrates provides the squirrel with a quick, much-needed energy source, especially during periods of food scarcity.
The inner bark also serves as a source of hydration and minerals when water is difficult to find, such as during dry periods or the frozen winter months. Bark stripping may also be driven by the need for calcium, particularly in late winter and early spring when female squirrels are pregnant or nursing. Gnawing on bark also helps squirrels maintain their continuously growing incisor teeth, ensuring they remain sharp and at a manageable length.
Preferred Trees and Seasonal Habits
Bark consumption is highly seasonal, peaking in late winter and early spring when natural food supplies like nuts and fruits are depleted, and trees begin moving sap. This period coincides with the time when the sap and inner tissues are most active and full of stored nutrients.
Squirrels exhibit preferences for certain tree species, generally targeting those with softer or thinner bark that is easier to chew through. Common targets include maple, elm, pine, beech, and honeylocust, as well as fruit trees like apple. The damage often focuses on younger trees or the thinner, upper branches of older trees, which are easier for the animals to access.
Assessing the Damage to Trees
When a squirrel removes a small patch of bark, the tree can usually heal itself by growing new tissue over the wound. However, the behavior becomes serious if the squirrel chews all the way around the circumference of a branch or trunk, a process known as girdling.
Girdling severs the tree’s vascular system, which is responsible for transporting water and nutrients between the roots and the canopy. If the damage completely encircles the main stem or a major limb, the portion of the tree above the girdle will die. Open wounds from bark stripping also leave the tree vulnerable to secondary attacks from insects, pests, and fungal diseases that can cause internal decay and structural weakness.
Deterring Bark-Eating Squirrels
One effective physical barrier involves wrapping the trunk with metal flashing or wire mesh. Ensure the material is held away from the bark to prevent direct access. The barrier should extend at least two feet high to make climbing difficult, but this method is ineffective if squirrels can jump from nearby structures or branches.
Taste-based repellents offer another approach, making the bark unpalatable to the animals. Commercial products often use capsaicin, the compound that gives chili peppers their heat, or strong scents like garlic or peppermint oil. Since these sprays are water-soluble, they require frequent reapplication, especially after rain, to maintain effectiveness. Providing alternative resources, such as a dedicated water source or a supplemental food station with nuts and seeds during the late winter and early spring, can also divert the animals’ attention away from valuable trees.