Deer consume tree bark, a behavior primarily observed when preferred food sources become scarce. This act, known as bark stripping, is a survival strategy, especially when softer vegetation is unavailable. Bark stripping is distinct from “rubbing,” where male deer remove velvet from their antlers and mark territory, though both activities damage the tree’s outer layers.
Why Deer Consume Tree Bark
Deer consume tree bark out of nutritional necessity when their typical diet of leaves, buds, and herbaceous plants is depleted. This behavior is most common during late winter or early spring when food scarcity is at its peak. The inner bark and cambium layer contain carbohydrates, starches, and trace minerals that provide a survival ration during harsh conditions.
Bark also supplies coarse roughage, which is important for maintaining the healthy function of the deer’s specialized digestive system, particularly the rumen. Deer are herbivores, and their diet must provide the bulk necessary for proper rumination. When palatable food is absent, deer turn to woody material to meet this dietary requirement.
Identifying Vulnerable Tree Species
Deer exhibit distinct preferences for trees with thin, smooth bark and high nutritional content. Young maples, fruit trees, poplars, and birches are vulnerable because their bark is easier to strip and often sweeter than that of older trees. Species like sycamore, beech, and certain oaks are also frequently damaged by deer seeking sustenance.
Deer avoid trees that possess strong chemical defenses, such as high-resin content or bitter compounds. For instance, evergreens like boxwood and certain pines with high resin concentration are less palatable. However, if the deer population is high and food is extremely limited, even less-preferred species may be targeted for survival.
Immediate and Long-Term Tree Damage
The primary damage caused by bark stripping is the interruption of the tree’s vascular system, a process known as girdling. When a deer strips the bark, they expose and often remove the phloem and cambium layers beneath the outer bark. The phloem transports sugars and nutrients produced by the leaves downward to the roots.
If the bark is removed completely around the circumference of the trunk, the flow of nutrients to the roots ceases, effectively starving the tree. This girdling action results in the slow death of the tree, which can take one to three years. Even partial damage leaves an open wound, making the tree susceptible to fungal infections, disease, and wood-boring insects. Studies show that trees with bark stripping damage can suffer significant reductions in growth, with mean volume losses around 41% compared to undamaged trees.
Protecting Trees from Bark Stripping
The most reliable strategy for preventing bark stripping damage is the use of physical barriers that prevent deer from accessing the trunk. Wrapping the lower portion of the trunk with commercial tree wrap or a sturdy material like hardware cloth is effective. This protection should extend from the ground up to at least four feet, covering the area most accessible to deer.
For young or high-value trees, constructing a physical cage or cylinder from wire mesh around the trunk offers robust protection against both feeding and antler rubbing damage. The mesh must be rigid enough to prevent deer from pressing against the bark and secured firmly to the ground. While commercial repellents can deter browsing by taste or smell, physical barriers provide a more consistent defense.