Squirrels are a common sight in many landscapes, often seen scampering up trees. However, their habit of chewing on tree bark can be puzzling. This activity leaves visible marks and often raises questions about why these agile rodents engage in such behavior.
Reasons Behind Bark Chewing
Squirrels chew on tree bark for several reasons, primarily nutritional needs. During periods when nuts, seeds, and fruits are scarce, especially in late winter or early spring, the inner cambium layer of the bark provides a valuable food source. This layer is rich in sugars, carbohydrates, and minerals, becoming appealing when other seasonal foods are unavailable.
Bark chewing also aids hydration, especially during dry periods or when water sources are limited. The moisture within the bark supplements their water intake. Additionally, squirrels, like all rodents, have continuously growing incisors. Gnawing on bark helps wear down these teeth, preventing overgrowth and maintaining dental health.
While less common than nutritional or dental reasons, squirrels also use bark for nesting material. They may peel off the outer, tougher bark to access the softer, fibrous inner bark. This material is used to line their nests, known as dreys, providing insulation and comfort.
Consequences for Trees
Squirrel bark chewing can have various consequences for trees, ranging from minor cosmetic damage to severe health issues. Girdling occurs when squirrels chew around the entire circumference of a tree or branch. This interrupts the tree’s vascular system, which transports nutrients. If enough of this layer is removed, it can starve the roots, leading to the death of the branch or even the entire tree.
Even partial bark removal stresses a tree, making it more susceptible to diseases and insect infestations. The exposed inner wood becomes vulnerable to fungi and bacteria, which can enter through these open wounds. Young trees and smaller branches are more vulnerable due to thinner bark, though main trunks can also be affected.
Protecting Your Trees
Protecting trees from squirrel bark chewing involves practical strategies. Physical barriers, such as tree wraps made of durable materials like metal flashing or wire mesh, can be installed around vulnerable tree trunks. These barriers should be at least two feet wide and extend five to six feet high to prevent squirrels from climbing.
Repellents offer another option, though their effectiveness can vary and they often require reapplication. Some commercial repellents contain capsaicin or other bitter-tasting compounds that deter squirrels. Applying these to affected bark might discourage further chewing; always follow product instructions.
Providing alternative food or water sources, such as a bird bath or a squirrel feeder away from susceptible trees, can reduce chewing incentives, especially during periods of scarcity. Maintaining overall tree health through proper watering, mulching, and pruning also helps. Healthy, vigorous trees are more resilient and better equipped to recover from minor damage. Trimming branches close to structures can also limit squirrel access points.